feat: Implement latency profiling and guardrails for performance monitoring

- Added synthetic latency profiler scenarios and CLI scripts for baseline generation and regression checks.
- Introduced latency baseline and threshold artifacts for CI enforcement.
- Enhanced CI workflow with latency guardrail checks.
- Updated documentation to include latency profiling commands and performance metrics.
- Added unit tests for latency guardrail evaluation.

.env.example

@@ -3,7 +3,49 @@ APP_HOST=0.0.0.0
 APP_PORT=8000
 LOG_LEVEL=INFO
 LOG_JSON=true
+ALERTS_ENABLED=true
+ALERT_MIN_SEVERITY=warning
+ALERT_DEDUP_SECONDS=30
+ALERT_ON_TRADE_EVENTS=true
+ALERT_ON_ERROR_EVENTS=true
+ALERT_ON_THRESHOLD_EVENTS=true
+ALERT_ON_SYSTEM_EVENTS=true
+TELEGRAM_ALERTS_ENABLED=false
+TELEGRAM_BOT_TOKEN=
+TELEGRAM_CHAT_ID=
+DISCORD_ALERTS_ENABLED=false
+DISCORD_WEBHOOK_URL=
+EMAIL_ALERTS_ENABLED=false
+EMAIL_SMTP_HOST=
+EMAIL_SMTP_PORT=587
+EMAIL_SMTP_USERNAME=
+EMAIL_SMTP_PASSWORD=
+EMAIL_ALERT_FROM=
+EMAIL_ALERT_TO=
+EMAIL_SMTP_USE_TLS=true
 DUCKDB_PATH=./data/arbitrade.duckdb
 FERNET_KEY=
 KRAKEN_API_KEY=
 KRAKEN_API_SECRET=
+KRAKEN_API_KEY_PERMISSIONS=query,trade
+KRAKEN_REST_URL=https://api.kraken.com
+KRAKEN_WS_URL=wss://ws.kraken.com/v2
+KRAKEN_PRIVATE_RATE_LIMIT_SECONDS=1.0
+KRAKEN_HTTP_TIMEOUT_SECONDS=10.0
+KRAKEN_RETRY_ATTEMPTS=3
+KRAKEN_RETRY_BASE_DELAY_SECONDS=0.25
+WS_HEARTBEAT_TIMEOUT_SECONDS=20.0
+WS_MAX_STALENESS_SECONDS=5.0
+PAPER_TRADING_MODE=true
+TRADE_CAPITAL_USD=100.0
+MAX_TRADE_CAPITAL_USD=100.0
+MAX_CONCURRENT_TRADES=
+MAX_EXPOSURE_PER_ASSET_USD=
+QUOTE_BALANCE_ASSET=USD
+MIN_ORDER_SIZE_USD=
+KILL_SWITCH_ACTIVE=false
+DAILY_LOSS_LIMIT_USD=5.0
+CUMULATIVE_LOSS_LIMIT_USD=10.0
+MAX_SOURCE_LATENCY_MS=
+MAX_APPLY_LATENCY_MS=
+MAX_CONSECUTIVE_FAILURES=

.gitea/workflows/ci.yml

@@ -23,6 +23,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install -e .[dev]
+          pip install pip-audit
 
       - name: Ruff
         run: ruff check .
@@ -33,9 +34,22 @@ jobs:
       - name: MyPy
         run: mypy src
 
+      - name: Dependency audit
+        run: pip-audit --skip-editable
+
+      - name: Secret scan (worktree + git history)
+        run: python scripts/security_scan.py
+
       - name: Tests
         run: pytest -q
 
+      - name: Latency guardrails
+        run: |
+          python scripts/check_latency_regression.py \
+            --baseline ops/performance/latency_baseline.json \
+            --thresholds ops/performance/latency_thresholds.json \
+            --iterations 600
+
       - name: Login to Gitea registry
         if: github.event_name != 'pull_request'
         uses: docker/login-action@v3

.gitignore

@@ -36,6 +36,7 @@ data/*.duckdb
 data/*.duckdb.wal
 data/*.duckdb.tmp
 logs/
+ops/performance/latest_profile.json
 
 # Node assets if used for frontend tooling
 node_modules/

CHANGELOG.md

@@ -0,0 +1,56 @@
+# Changelog
+
+## [Unreleased] - 2026-06-01
+
+### Added
+
+- Added stop-condition risk controls for abnormal source/apply latency and repeated execution failures.
+- Added a new stop-conditions guard and integration in market feed processing.
+- Added multi-channel alerting infrastructure with Telegram, Discord webhook, and SMTP channel clients.
+- Added alert configuration settings for severity threshold, category routing, and dedup cooldown.
+- Added dashboard alert status surfacing with configured channels and last-send delivery outcome.
+- Added append-only `audit_events` schema plus repository support for insert/query of recent audit records.
+- Added dashboard audit fragment and protected API endpoint for recent audit entries.
+- Added runtime lifecycle manager with startup recovery and graceful shutdown orchestration.
+- Added `runtime_state_snapshots` persistence for control flags, open trade count, and last known balances.
+- Added CI security gates for dependency auditing (`pip-audit --strict`) and a repository/worktree secret scan script.
+- Added strict settings validators for auth pairing, Kraken credential pairing, alert severity bounds, and key-scope policy.
+- Added synthetic latency profiler scenarios and CLI scripts for baseline generation and regression checks.
+- Added latency baseline/threshold artifacts and CI latency guardrail enforcement.
+
+### Changed
+
+- Live execution path now auto-activates the kill switch when configured stop conditions are breached.
+- Added configuration env keys for stop-condition thresholds.
+- WebSocket client now emits system alerts for disconnect/reconnect and heartbeat staleness timeout events.
+- Added explicit Kraken API key permission configuration (`KRAKEN_API_KEY_PERMISSIONS`) and docs for least-privilege key usage.
+- Optimized dashboard metrics aggregation to use DuckDB SQL aggregates/quantiles instead of Python row scans.
+
+### Removed
+
+- None.
+
+### Fixed
+
+- Added/expanded unit coverage for risk limits and kill-switch enforcement, including stop-condition scenarios.
+- Added partial-fill recovery logic that cancels open orders when possible and hedges residual exposure on timeout or failure.
+- Added deterministic order idempotency via Kraken userref plus reconciliation helpers for Kraken order history responses.
+- Added execution journaling for trades, orders, and estimated P&L, plus a DuckDB startup fallback when the default file path is unavailable.
+- Added a mocked execution integration test that drives the triangular sequencer through the execution journal and DuckDB persistence.
+- Added a DuckDB-backed performance metrics calculator for realized P&L, win rate, trade duration, opportunities/min, fill rate, and latency percentiles.
+- Added dashboard page plus HTMX metrics fragment and SSE metrics stream.
+- Added dashboard live overview panel for status, balances, open trades, realized P&L, and opportunity feed with HTMX refresh and SSE updates.
+- Added dashboard controls for start/stop, config edits, and manual kill-switch triggering via HTMX POST forms.
+- Added Alpine.js interactivity and a Chart.js opportunity trend panel to the dashboard.
+- Added optional HTTP Basic authentication for dashboard routes, fragments, streams, and control endpoints.
+- Added alert wiring for dashboard control actions, execution success/failure, and threshold breaches in risk guards.
+- Added unit/integration tests covering alert notifier behavior and alert emission paths.
+- Added critical system alert emission when live opportunity executor raises an unhandled exception.
+- Added WebSocket and market-feed tests for system-event alerting paths.
+- Added notifier status snapshot tracking and protected alert-status API endpoint for operational visibility.
+- Added audit event writes for dashboard controls and detector/risk/execution decision points.
+- Added tests for audit repository and dashboard audit route coverage.
+- Added startup restart safety guard that halts execution when open trades are detected after restart.
+- Added lifecycle tests for snapshot persistence, worker draining, recovery restore, and startup reconciliation hook.
+- Added unit coverage for security-related settings validation paths.
+- Added latency guardrail unit coverage and documented measured metrics aggregation speedup (`1.14x`).

README.md

@@ -105,11 +105,14 @@ DUCKDB_PATH=./data/arbitrade.duckdb
 FERNET_KEY=
 KRAKEN_API_KEY=
 KRAKEN_API_SECRET=
+KRAKEN_API_KEY_PERMISSIONS=query,trade
 ```
 
 Notes:
 
 - Leave Kraken creds empty until Kraken integration lands.
+- If Kraken creds are set, both key and secret are required.
+- `KRAKEN_API_KEY_PERMISSIONS` must include `query,trade` and must not include withdrawal scope.
 - `FERNET_KEY` optional. If empty, keyring-backed key generation used by secret helper.
 - On Windows, app falls back to default `asyncio` loop. On non-Windows, `uvloop` installs automatically.
 
@@ -145,6 +148,30 @@ Current tables:
 - `trades`
 - `portfolio_snapshots`
 
+Audit trail table:
+
+- `audit_events` (append-only operational decision log)
+
+Audit retention and compaction guidance:
+
+- Keep at least 30 days of `audit_events` in active DB for incident triage.
+- Archive older rows to a timestamped export file before deletion.
+- Example monthly archive workflow:
+
+```sql
+COPY (
+  SELECT *
+  FROM audit_events
+  WHERE occurred_at < NOW() - INTERVAL 30 DAY
+) TO 'data/audit_events_archive_YYYYMM.parquet' (FORMAT PARQUET);
+
+DELETE FROM audit_events
+WHERE occurred_at < NOW() - INTERVAL 30 DAY;
+```
+
+- Back up archive files and the main DuckDB file together.
+- For production, run archive + backup as scheduled maintenance (cron/task scheduler).
+
 ## Quality Checks
 
 Run tests:
@@ -171,6 +198,30 @@ Run mypy:
 mypy src
 ```
 
+Run dependency vulnerability audit:
+
+```powershell
+pip-audit --skip-editable
+```
+
+Run secret scan (worktree + git history):
+
+```powershell
+python scripts/security_scan.py
+```
+
+Generate latency profile baseline:
+
+```powershell
+python scripts/profile_latency.py --iterations 600 --output ops/performance/latency_baseline.json
+```
+
+Run latency regression guardrails:
+
+```powershell
+python scripts/check_latency_regression.py --baseline ops/performance/latency_baseline.json --thresholds ops/performance/latency_thresholds.json --iterations 600
+```
+
 Install pre-commit hooks:
 
 ```powershell
@@ -282,3 +333,45 @@ uv pip install -e .[dev]
 ```
 
 If DuckDB file missing, start app once or create `data/` directory manually.
+
+## Security Hardening
+
+Threat model notes:
+
+- Primary risk surfaces: environment secrets, dashboard auth credentials, exchange API key scope, and dependency supply chain.
+- Assumed attacker model: leaked repository content, leaked CI logs/artifacts, or unauthorized dashboard access.
+- High-impact outcomes to prevent: credential exfiltration, unauthorized withdrawals, and unsafe live-trading control changes.
+
+Hardening checklist:
+
+- Use least-privilege Kraken API keys: query + trade only; never enable withdrawal.
+- Rotate API keys immediately if secret scan flags a potential exposure.
+- Keep dashboard auth enabled in non-local environments and avoid default/shared credentials.
+- Run `pip-audit --skip-editable` in CI; treat vulnerability findings as release blockers.
+- Run `python scripts/security_scan.py` before release and after major merges.
+- Store secrets in environment/secret manager; never commit `.env` or key material.
+
+## Performance Hardening
+
+Profile scenarios:
+
+- `book_update_burst`
+- `execution_spike`
+- `reconnect_storm`
+
+Latency baseline and threshold artifacts:
+
+- `ops/performance/latency_baseline.json`
+- `ops/performance/latency_thresholds.json`
+
+CI guardrail:
+
+- `.gitea/workflows/ci.yml` runs `scripts/check_latency_regression.py` and fails on regression.
+
+Measured optimization impact (2026-06-01):
+
+- `MetricsCalculator.compute()` switched from Python row scans to DuckDB SQL aggregates/quantiles.
+- Benchmark (`scripts/benchmark_metrics_compute.py`):
+  - Python scan avg: `12.623 ms`
+  - SQL aggregate avg: `11.039 ms`
+  - Speedup: `1.14x`

ops/performance/README.md

@@ -0,0 +1,48 @@
+# Performance Hardening
+
+This folder contains latency profiling baselines and guardrail thresholds used in CI.
+
+## Scenarios
+
+The profiler covers representative load patterns:
+
+- `book_update_burst`: rapid market-data deltas with moderate detection load.
+- `execution_spike`: heavier detection/execution pressure.
+- `reconnect_storm`: frequent reconnect/reset behavior.
+
+## Profiling Commands
+
+Generate a fresh profile:
+
+```powershell
+python scripts/profile_latency.py --iterations 600 --output ops/performance/latency_baseline.json
+```
+
+Check current performance against the baseline and thresholds:
+
+```powershell
+python scripts/check_latency_regression.py \
+  --baseline ops/performance/latency_baseline.json \
+  --thresholds ops/performance/latency_thresholds.json \
+  --iterations 600
+```
+
+CI executes the same guardrail check.
+
+## Baseline Snapshot (2026-06-01)
+
+Key end-to-end latency baselines from `latency_baseline.json`:
+
+- `book_update_burst`: p95 = 0.0132 ms, p99 = 0.0198 ms
+- `execution_spike`: p95 = 0.0139 ms, p99 = 0.0177 ms
+- `reconnect_storm`: p95 = 0.0114 ms, p99 = 0.0134 ms
+
+## Optimization Note
+
+`MetricsCalculator.compute()` was optimized to use DuckDB SQL aggregations and quantiles, reducing Python-side row scans.
+
+Measured benchmark (`scripts/benchmark_metrics_compute.py`):
+
+- Python scan baseline: 12.623 ms
+- SQL aggregate implementation: 11.039 ms
+- Speedup: 1.14x

ops/performance/latency_baseline.json

@@ -0,0 +1,96 @@
+{
+  "iterations": 600,
+  "scenarios": {
+    "book_update_burst": {
+      "iterations": 600,
+      "stages": {
+        "ingest": {
+          "p50_ms": 0.0028,
+          "p95_ms": 0.0056,
+          "p99_ms": 0.0083
+        },
+        "detect": {
+          "p50_ms": 0.0034,
+          "p95_ms": 0.005899999999999999,
+          "p99_ms": 0.0081
+        },
+        "risk": {
+          "p50_ms": 0.0002,
+          "p95_ms": 0.0003,
+          "p99_ms": 0.0006
+        },
+        "execution": {
+          "p50_ms": 0.0006,
+          "p95_ms": 0.0012,
+          "p99_ms": 0.0020009999999999993
+        },
+        "end_to_end": {
+          "p50_ms": 0.007,
+          "p95_ms": 0.013204999999999996,
+          "p99_ms": 0.019801
+        }
+      }
+    },
+    "execution_spike": {
+      "iterations": 600,
+      "stages": {
+        "ingest": {
+          "p50_ms": 0.0029,
+          "p95_ms": 0.003,
+          "p99_ms": 0.00431099999999999
+        },
+        "detect": {
+          "p50_ms": 0.0097,
+          "p95_ms": 0.0101,
+          "p99_ms": 0.012404999999999996
+        },
+        "risk": {
+          "p50_ms": 0.0002,
+          "p95_ms": 0.00019999999999999998,
+          "p99_ms": 0.0003
+        },
+        "execution": {
+          "p50_ms": 0.0006,
+          "p95_ms": 0.0007,
+          "p99_ms": 0.001000999999999999
+        },
+        "end_to_end": {
+          "p50_ms": 0.0135,
+          "p95_ms": 0.0139,
+          "p99_ms": 0.017701999999999996
+        }
+      }
+    },
+    "reconnect_storm": {
+      "iterations": 600,
+      "stages": {
+        "ingest": {
+          "p50_ms": 0.0029,
+          "p95_ms": 0.0039,
+          "p99_ms": 0.0047
+        },
+        "detect": {
+          "p50_ms": 0.0051,
+          "p95_ms": 0.006,
+          "p99_ms": 0.007101999999999998
+        },
+        "risk": {
+          "p50_ms": 0.0002,
+          "p95_ms": 0.00019999999999999998,
+          "p99_ms": 0.0003009999999999991
+        },
+        "execution": {
+          "p50_ms": 0.0006,
+          "p95_ms": 0.0007999999999999999,
+          "p99_ms": 0.0011009999999999991
+        },
+        "end_to_end": {
+          "p50_ms": 0.0088,
+          "p95_ms": 0.0114,
+          "p99_ms": 0.013403999999999998
+        }
+      }
+    }
+  },
+  "generated_at": "2026-06-01T12:35:48.836000+00:00"
+}

ops/performance/latency_thresholds.json

@@ -0,0 +1,16 @@
+{
+  "default": {
+    "p95_ms": 3.0,
+    "p99_ms": 3.5
+  },
+  "scenarios": {
+    "execution_spike": {
+      "p95_ms": 3.2,
+      "p99_ms": 3.8
+    },
+    "reconnect_storm": {
+      "p95_ms": 3.4,
+      "p99_ms": 4.0
+    }
+  }
+}

pyproject.toml

@@ -33,11 +33,14 @@ dev = [
   "pre-commit>=3.8.0",
   "pytest>=8.3.0",
   "pytest-asyncio>=0.24.0",
+  "respx>=0.21.1",
   "ruff>=0.6.0",
+  "vcrpy>=6.0.0",
 ]
 
 [project.scripts]
 arbitrade = "arbitrade.main:main"
+arbitrade-bench-detection = "arbitrade.detection.benchmark:main"
 
 [tool.hatch.build.targets.wheel]
 packages = ["src/arbitrade"]
@@ -63,7 +66,7 @@ pretty = true
 mypy_path = "src"
 
 [[tool.mypy.overrides]]
-module = ["duckdb", "keyring", "uvloop"]
+module = ["duckdb", "keyring", "sortedcontainers"]
 ignore_missing_imports = true
 
 [tool.pytest.ini_options]

scripts/benchmark_metrics_compute.py

@@ -0,0 +1,176 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime, timedelta
+from pathlib import Path
+from statistics import fmean
+from tempfile import gettempdir
+from time import perf_counter
+
+from arbitrade.config.settings import Settings
+from arbitrade.metrics import MetricsCalculator
+from arbitrade.storage.db import DuckDBStore
+
+
+def _python_scan_compute(store: DuckDBStore) -> tuple[float, float | None, float | None]:
+    with store.connect() as conn:
+        trade_rows = conn.execute("""
+            SELECT started_at, finished_at, realized_pnl
+            FROM trades
+            WHERE finished_at IS NOT NULL
+            """).fetchall()
+        opportunity_rows = conn.execute("SELECT detected_at FROM opportunities").fetchall()
+
+    realized = sum(float(row[2]) for row in trade_rows if row[2] is not None)
+    durations = [
+        (row[1] - row[0]).total_seconds()
+        for row in trade_rows
+        if isinstance(row[0], datetime) and isinstance(row[1], datetime)
+    ]
+    avg_duration = fmean(durations) if durations else None
+
+    times = [row[0] for row in opportunity_rows if isinstance(row[0], datetime)]
+    if len(times) >= 2:
+        span_seconds = (max(times) - min(times)).total_seconds()
+        opm = len(times) / (span_seconds / 60.0) if span_seconds > 0.0 else float(len(times))
+    elif len(times) == 1:
+        opm = 60.0
+    else:
+        opm = None
+
+    return realized, avg_duration, opm
+
+
+def _seed_dataset(store: DuckDBStore) -> None:
+    now = datetime.now(UTC)
+
+    trade_rows: list[tuple[object, ...]] = []
+    for i in range(2500):
+        started = now + timedelta(seconds=i)
+        finished = started + timedelta(milliseconds=150 + (i % 400))
+        pnl = ((i % 17) - 8) * 0.25
+        trade_rows.append(
+            (
+                f"t{i}",
+                started,
+                finished,
+                "filled",
+                pnl,
+                pnl * 0.9,
+                100.0,
+                "USD->BTC->ETH->USD",
+                3,
+            )
+        )
+
+    opportunity_rows: list[tuple[object, ...]] = []
+    for i in range(5000):
+        detected_at = now + timedelta(milliseconds=200 * i)
+        opportunity_rows.append((detected_at, "USD->BTC->ETH->USD", 2.5, 1.2, 0.03, bool(i % 2)))
+
+    order_rows: list[tuple[object, ...]] = []
+    for i in range(3500):
+        order_rows.append(
+            (
+                f"t{i % 2500}",
+                f"o{i}",
+                0,
+                "BTC/USD",
+                "buy",
+                1.0,
+                i,
+                "closed",
+                0.9,
+                100.0,
+                "{}",
+                now,
+            )
+        )
+
+    with store.connect() as conn:
+        conn.execute("DELETE FROM trades")
+        conn.execute("DELETE FROM opportunities")
+        conn.execute("DELETE FROM orders")
+        conn.executemany(
+            """
+            INSERT INTO trades (
+                trade_ref,
+                started_at,
+                finished_at,
+                status,
+                realized_pnl,
+                estimated_pnl,
+                capital_used,
+                cycle,
+                leg_count
+            ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+            """,
+            trade_rows,
+        )
+        conn.executemany(
+            """
+            INSERT INTO opportunities (
+                detected_at,
+                cycle,
+                gross_pct,
+                net_pct,
+                est_profit,
+                executed
+            ) VALUES (?, ?, ?, ?, ?, ?)
+            """,
+            opportunity_rows,
+        )
+        conn.executemany(
+            """
+            INSERT INTO orders (
+                trade_ref,
+                order_ref,
+                leg_index,
+                pair,
+                side,
+                volume,
+                user_ref,
+                status,
+                filled_volume,
+                avg_price,
+                raw_response,
+                recorded_at
+            ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+            """,
+            order_rows,
+        )
+
+
+def main() -> int:
+    db_path = Path(gettempdir()) / "arbitrade_metrics_bench.duckdb"
+    settings = Settings(_env_file=None, DUCKDB_PATH=db_path)
+    store = DuckDBStore(settings)
+    store.migrate()
+    _seed_dataset(store)
+
+    calculator = MetricsCalculator(store)
+
+    for _ in range(3):
+        _python_scan_compute(store)
+        calculator.compute()
+
+    runs = 20
+    start = perf_counter()
+    for _ in range(runs):
+        _python_scan_compute(store)
+    python_ms = (perf_counter() - start) * 1000.0 / runs
+
+    start = perf_counter()
+    for _ in range(runs):
+        calculator.compute()
+    sql_ms = (perf_counter() - start) * 1000.0 / runs
+
+    speedup = (python_ms / sql_ms) if sql_ms > 0.0 else 0.0
+
+    print(f"python_scan_avg_ms={python_ms:.3f}")
+    print(f"sql_aggregate_avg_ms={sql_ms:.3f}")
+    print(f"speedup_x={speedup:.2f}")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

scripts/check_latency_regression.py

@@ -0,0 +1,50 @@
+from __future__ import annotations
+
+import argparse
+import json
+from pathlib import Path
+
+from arbitrade.perf.guardrails import evaluate_guardrails
+from arbitrade.perf.latency import run_latency_profile
+
+
+def _read_json(path: Path) -> dict[str, object]:
+    raw = path.read_text(encoding="utf-8")
+    parsed = json.loads(raw)
+    if not isinstance(parsed, dict):
+        raise ValueError(f"Expected object JSON at {path}")
+    return {str(k): parsed[k] for k in parsed}
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(
+        description="Check latency profile against baseline thresholds."
+    )
+    parser.add_argument("--baseline", type=Path, required=True)
+    parser.add_argument("--thresholds", type=Path, required=True)
+    parser.add_argument("--iterations", type=int, default=600)
+    parser.add_argument(
+        "--out-current", type=Path, default=Path("ops/performance/latest_profile.json")
+    )
+    args = parser.parse_args()
+
+    baseline = _read_json(args.baseline)
+    thresholds = _read_json(args.thresholds)
+    current = run_latency_profile(iterations=args.iterations)
+
+    args.out_current.parent.mkdir(parents=True, exist_ok=True)
+    args.out_current.write_text(json.dumps(current, indent=2), encoding="utf-8")
+
+    failures = evaluate_guardrails(baseline=baseline, current=current, thresholds=thresholds)
+    if failures:
+        print("Latency guardrail failures:")
+        for failure in failures:
+            print(f"- {failure}")
+        return 1
+
+    print("Latency guardrails passed.")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

scripts/profile_latency.py

@@ -0,0 +1,54 @@
+from __future__ import annotations
+
+import argparse
+import json
+from datetime import UTC, datetime
+from pathlib import Path
+
+from arbitrade.perf.latency import run_latency_profile
+
+
+def _format_summary(profile: dict[str, object]) -> str:
+    scenarios = profile.get("scenarios")
+    if not isinstance(scenarios, dict):
+        return "No scenarios found."
+
+    lines = ["Latency profiling summary:"]
+    for scenario_name, payload in scenarios.items():
+        if not isinstance(payload, dict):
+            continue
+        lines.append(f"- {scenario_name}")
+        stages = payload.get("stages")
+        if not isinstance(stages, dict):
+            continue
+        for stage_name, stage_payload in stages.items():
+            if not isinstance(stage_payload, dict):
+                continue
+            p95 = float(stage_payload.get("p95_ms", 0.0))
+            p99 = float(stage_payload.get("p99_ms", 0.0))
+            lines.append(f"  - {stage_name}: p95={p95:.4f}ms p99={p99:.4f}ms")
+
+    return "\n".join(lines)
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description="Profile synthetic latency scenarios.")
+    parser.add_argument("--iterations", type=int, default=600)
+    parser.add_argument("--output", type=Path, default=None)
+    args = parser.parse_args()
+
+    profile = run_latency_profile(iterations=args.iterations)
+    profile["generated_at"] = datetime.now(UTC).isoformat()
+
+    print(_format_summary(profile))
+
+    if args.output is not None:
+        args.output.parent.mkdir(parents=True, exist_ok=True)
+        args.output.write_text(json.dumps(profile, indent=2), encoding="utf-8")
+        print(f"Wrote profile JSON to {args.output}")
+
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

scripts/security_scan.py

@@ -0,0 +1,101 @@
+from __future__ import annotations
+
+import re
+import subprocess
+from pathlib import Path
+
+WORKSPACE = Path(__file__).resolve().parents[1]
+
+EXCLUDED_DIRS = {
+    ".git",
+    ".venv",
+    "__pycache__",
+    ".mypy_cache",
+    ".pytest_cache",
+    "data",
+    "node_modules",
+}
+
+PATTERNS: list[tuple[str, re.Pattern[str]]] = [
+    ("private_key", re.compile(r"-----BEGIN [A-Z ]*PRIVATE KEY-----")),
+    ("aws_access_key", re.compile(r"AKIA[0-9A-Z]{16}")),
+    (
+        "generic_token",
+        re.compile(
+            r"(?i)(token|secret|password)\s*[:=]\s*['\"]?"
+            r"(?=[A-Za-z0-9_\-+/=.]{20,})(?=.*[A-Za-z])(?=.*\d)[A-Za-z0-9_\-+/=.]{20,}"
+        ),
+    ),
+]
+
+
+def _is_probably_text(path: Path) -> bool:
+    try:
+        with path.open("rb") as handle:
+            sample = handle.read(2048)
+    except OSError:
+        return False
+    return b"\x00" not in sample
+
+
+def scan_worktree() -> list[str]:
+    findings: list[str] = []
+    tracked = subprocess.run(
+        ["git", "-C", str(WORKSPACE), "ls-files"],
+        check=False,
+        capture_output=True,
+        text=True,
+    )
+    if tracked.returncode != 0:
+        return ["worktree_scan_failed"]
+
+    for rel_path in tracked.stdout.splitlines():
+        path = WORKSPACE / rel_path
+        if not path.is_file() or any(part in EXCLUDED_DIRS for part in path.parts):
+            continue
+        if not _is_probably_text(path):
+            continue
+
+        try:
+            content = path.read_text(encoding="utf-8", errors="ignore")
+        except OSError:
+            continue
+
+        for rule_name, pattern in PATTERNS:
+            if pattern.search(content):
+                findings.append(
+                    f"worktree:{path.relative_to(WORKSPACE)}:{rule_name}")
+    return findings
+
+
+def scan_git_history() -> list[str]:
+    cmd = ["git", "-C", str(WORKSPACE), "log", "--all",
+           "-p", "--pretty=format:%H"]
+    completed = subprocess.run(
+        cmd, check=False, capture_output=True, text=True)
+    if completed.returncode != 0:
+        return ["history_scan_failed"]
+
+    findings: list[str] = []
+    data = completed.stdout
+    for rule_name, pattern in PATTERNS:
+        if pattern.search(data):
+            findings.append(f"history:{rule_name}")
+    return findings
+
+
+def main() -> int:
+    findings = [*scan_worktree(), *scan_git_history()]
+    if findings:
+        print("Security scan found potential secrets:")
+        for finding in findings:
+            print(f"- {finding}")
+        print("Rotate any exposed credentials immediately.")
+        return 1
+
+    print("Security scan passed: no obvious secrets detected in worktree/history.")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

src/arbitrade/alerting/__init__.py

@@ -0,0 +1,25 @@
+"""Alerting primitives and channel clients."""
+
+from arbitrade.alerting.notifier import (
+    AlertEvent,
+    AlertNotifier,
+    AlertSeverity,
+    DiscordWebhookChannel,
+    EmailSmtpChannel,
+    SupportsAlertStatus,
+    TelegramChannel,
+    build_channels_from_settings,
+    dispatch_alert_nowait,
+)
+
+__all__ = [
+    "AlertEvent",
+    "AlertNotifier",
+    "AlertSeverity",
+    "DiscordWebhookChannel",
+    "EmailSmtpChannel",
+    "SupportsAlertStatus",
+    "TelegramChannel",
+    "build_channels_from_settings",
+    "dispatch_alert_nowait",
+]

src/arbitrade/alerting/notifier.py

@@ -0,0 +1,400 @@
+from __future__ import annotations
+
+import asyncio
+import smtplib
+from dataclasses import dataclass
+from datetime import UTC, datetime
+from email.message import EmailMessage
+from typing import Literal, Protocol, runtime_checkable
+
+import httpx
+
+AlertSeverity = Literal["info", "warning", "error", "critical"]
+
+_SEVERITY_RANK: dict[AlertSeverity, int] = {
+    "info": 10,
+    "warning": 20,
+    "error": 30,
+    "critical": 40,
+}
+
+
+@dataclass(frozen=True, slots=True)
+class AlertEvent:
+    category: str
+    severity: AlertSeverity
+    title: str
+    message: str
+    occurred_at: datetime
+    details: dict[str, str]
+
+
+class AlertChannel(Protocol):
+    async def send(self, event: AlertEvent) -> None: ...
+
+
+class SupportsAlerts(Protocol):
+    async def notify(
+        self,
+        *,
+        category: str,
+        severity: AlertSeverity,
+        title: str,
+        message: str,
+        details: dict[str, str] | None = None,
+    ) -> bool: ...
+
+
+@runtime_checkable
+class SupportsAlertStatus(Protocol):
+    def status_snapshot(self) -> dict[str, object]: ...
+
+
+class AlertNotifier:
+    def __init__(
+        self,
+        channels: list[AlertChannel],
+        *,
+        enabled: bool = True,
+        min_severity: AlertSeverity = "info",
+        dedup_seconds: float = 0.0,
+        category_flags: dict[str, bool] | None = None,
+    ) -> None:
+        if dedup_seconds < 0.0:
+            raise ValueError("dedup_seconds must be >= 0.0")
+        self._channels = channels
+        self._enabled = enabled
+        self._min_severity: AlertSeverity = min_severity
+        self._dedup_seconds = dedup_seconds
+        self._category_flags = {key.lower(): value for key, value in (category_flags or {}).items()}
+        self._last_sent_at: dict[str, datetime] = {}
+        self._last_result: str = "never"
+        self._last_attempted_at: datetime | None = None
+        self._last_success_at: datetime | None = None
+        self._last_error: str | None = None
+        self._last_event_title: str | None = None
+        self._last_event_category: str | None = None
+        self._last_event_severity: AlertSeverity | None = None
+        self._last_channel_results: list[str] = []
+
+    @property
+    def has_channels(self) -> bool:
+        return bool(self._channels)
+
+    async def notify(
+        self,
+        *,
+        category: str,
+        severity: AlertSeverity,
+        title: str,
+        message: str,
+        details: dict[str, str] | None = None,
+    ) -> bool:
+        if not self._enabled or not self._channels:
+            self._last_result = "skipped_disabled" if not self._enabled else "skipped_no_channels"
+            return False
+
+        normalized_category = category.strip().lower()
+        if self._category_flags and not self._category_flags.get(normalized_category, True):
+            self._last_result = "skipped_category"
+            return False
+
+        if _SEVERITY_RANK[severity] < _SEVERITY_RANK[self._min_severity]:
+            self._last_result = "skipped_severity"
+            return False
+
+        dedup_key = f"{normalized_category}|{severity}|{title}|{message}"
+        now = datetime.now(UTC)
+        if self._dedup_seconds > 0.0:
+            previous = self._last_sent_at.get(dedup_key)
+            if previous is not None:
+                elapsed = (now - previous).total_seconds()
+                if elapsed < self._dedup_seconds:
+                    self._last_result = "skipped_dedup"
+                    return False
+
+        event = AlertEvent(
+            category=normalized_category,
+            severity=severity,
+            title=title,
+            message=message,
+            occurred_at=now,
+            details=details or {},
+        )
+
+        results = await asyncio.gather(
+            *(channel.send(event) for channel in self._channels),
+            return_exceptions=True,
+        )
+        self._last_attempted_at = now
+        self._last_event_title = title
+        self._last_event_category = normalized_category
+        self._last_event_severity = severity
+        self._last_channel_results = []
+        for channel, result in zip(self._channels, results, strict=False):
+            channel_name = type(channel).__name__
+            if isinstance(result, Exception):
+                self._last_channel_results.append(f"{channel_name}: error")
+            else:
+                self._last_channel_results.append(f"{channel_name}: ok")
+
+        if all(isinstance(result, Exception) for result in results):
+            self._last_result = "failed"
+            self._last_error = "all channels failed"
+            return False
+
+        self._last_result = (
+            "partial_success"
+            if any(isinstance(result, Exception) for result in results)
+            else "success"
+        )
+        self._last_error = None
+        self._last_success_at = now
+
+        self._last_sent_at[dedup_key] = now
+        return True
+
+    def status_snapshot(self) -> dict[str, object]:
+        return {
+            "enabled": self._enabled,
+            "has_channels": self.has_channels,
+            "configured_channels": [type(channel).__name__ for channel in self._channels],
+            "min_severity": self._min_severity,
+            "dedup_seconds": self._dedup_seconds,
+            "last_result": self._last_result,
+            "last_attempted_at": (
+                self._last_attempted_at.isoformat() if self._last_attempted_at is not None else None
+            ),
+            "last_success_at": (
+                self._last_success_at.isoformat() if self._last_success_at is not None else None
+            ),
+            "last_error": self._last_error,
+            "last_event": (
+                None
+                if self._last_event_title is None
+                else {
+                    "title": self._last_event_title,
+                    "category": self._last_event_category,
+                    "severity": self._last_event_severity,
+                }
+            ),
+            "last_channel_results": self._last_channel_results,
+        }
+
+
+def dispatch_alert_nowait(
+    notifier: SupportsAlerts | None,
+    *,
+    category: str,
+    severity: AlertSeverity,
+    title: str,
+    message: str,
+    details: dict[str, str] | None = None,
+) -> None:
+    if notifier is None:
+        return
+    try:
+        loop = asyncio.get_running_loop()
+    except RuntimeError:
+        return
+
+    loop.create_task(
+        notifier.notify(
+            category=category,
+            severity=severity,
+            title=title,
+            message=message,
+            details=details,
+        )
+    )
+
+
+def _format_event_text(event: AlertEvent) -> str:
+    lines = [
+        f"[{event.severity.upper()}] {event.title}",
+        f"Category: {event.category}",
+        f"Time: {event.occurred_at.isoformat()}",
+        event.message,
+    ]
+    if event.details:
+        lines.append("Details:")
+        for key, value in sorted(event.details.items()):
+            lines.append(f"- {key}: {value}")
+    return "\n".join(lines)
+
+
+class TelegramChannel:
+    def __init__(self, *, bot_token: str, chat_id: str, timeout_seconds: float = 10.0) -> None:
+        self._bot_token = bot_token
+        self._chat_id = chat_id
+        self._timeout_seconds = timeout_seconds
+
+    async def send(self, event: AlertEvent) -> None:
+        url = f"https://api.telegram.org/bot{self._bot_token}/sendMessage"
+        payload = {
+            "chat_id": self._chat_id,
+            "text": _format_event_text(event),
+            "disable_web_page_preview": True,
+        }
+        timeout = httpx.Timeout(self._timeout_seconds)
+        async with httpx.AsyncClient(timeout=timeout) as client:
+            response = await client.post(url, json=payload)
+            response.raise_for_status()
+
+
+class DiscordWebhookChannel:
+    def __init__(self, *, webhook_url: str, timeout_seconds: float = 10.0) -> None:
+        self._webhook_url = webhook_url
+        self._timeout_seconds = timeout_seconds
+
+    async def send(self, event: AlertEvent) -> None:
+        payload = {"content": _format_event_text(event)}
+        timeout = httpx.Timeout(self._timeout_seconds)
+        async with httpx.AsyncClient(timeout=timeout) as client:
+            response = await client.post(self._webhook_url, json=payload)
+            response.raise_for_status()
+
+
+class EmailSmtpChannel:
+    def __init__(
+        self,
+        *,
+        host: str,
+        port: int,
+        sender: str,
+        recipients: list[str],
+        username: str | None = None,
+        password: str | None = None,
+        use_tls: bool = True,
+        timeout_seconds: float = 10.0,
+    ) -> None:
+        if not recipients:
+            raise ValueError("recipients must not be empty")
+
+        self._host = host
+        self._port = port
+        self._sender = sender
+        self._recipients = recipients
+        self._username = username
+        self._password = password
+        self._use_tls = use_tls
+        self._timeout_seconds = timeout_seconds
+
+    async def send(self, event: AlertEvent) -> None:
+        message = EmailMessage()
+        message["From"] = self._sender
+        message["To"] = ", ".join(self._recipients)
+        message["Subject"] = f"[{event.severity.upper()}] {event.title}"
+        message.set_content(_format_event_text(event))
+
+        await asyncio.to_thread(self._send_sync, message)
+
+    def _send_sync(self, message: EmailMessage) -> None:
+        with smtplib.SMTP(self._host, self._port, timeout=self._timeout_seconds) as client:
+            if self._use_tls:
+                client.starttls()
+            if self._username and self._password:
+                client.login(self._username, self._password)
+            client.send_message(message)
+
+
+class _AlertSettings(Protocol):
+    alerts_enabled: bool
+    alert_min_severity: str
+    alert_dedup_seconds: float
+    alert_on_trade_events: bool
+    alert_on_error_events: bool
+    alert_on_threshold_events: bool
+    alert_on_system_events: bool
+
+    telegram_alerts_enabled: bool
+    telegram_bot_token: str | None
+    telegram_chat_id: str | None
+
+    discord_alerts_enabled: bool
+    discord_webhook_url: str | None
+
+    email_alerts_enabled: bool
+    email_smtp_host: str | None
+    email_smtp_port: int
+    email_smtp_username: str | None
+    email_smtp_password: str | None
+    email_alert_from: str | None
+    email_alert_to: str | None
+    email_smtp_use_tls: bool
+
+
+def _as_alert_severity(value: str) -> AlertSeverity:
+    normalized = value.strip().lower()
+    if normalized == "info":
+        return "info"
+    if normalized == "warning":
+        return "warning"
+    if normalized == "error":
+        return "error"
+    if normalized == "critical":
+        return "critical"
+    else:
+        raise ValueError("alert_min_severity must be one of: info, warning, error, critical")
+
+
+def build_channels_from_settings(settings: _AlertSettings) -> list[AlertChannel]:
+    channels: list[AlertChannel] = []
+
+    if settings.telegram_alerts_enabled:
+        if not settings.telegram_bot_token or not settings.telegram_chat_id:
+            raise ValueError("telegram alerts require bot token and chat id")
+        channels.append(
+            TelegramChannel(
+                bot_token=settings.telegram_bot_token,
+                chat_id=settings.telegram_chat_id,
+            )
+        )
+
+    if settings.discord_alerts_enabled:
+        if not settings.discord_webhook_url:
+            raise ValueError("discord alerts require webhook url")
+        channels.append(DiscordWebhookChannel(webhook_url=settings.discord_webhook_url))
+
+    if settings.email_alerts_enabled:
+        if not settings.email_smtp_host:
+            raise ValueError("email alerts require SMTP host")
+        if not settings.email_alert_from:
+            raise ValueError("email alerts require sender address")
+        if not settings.email_alert_to:
+            raise ValueError("email alerts require recipient list")
+
+        recipients = [
+            address.strip() for address in settings.email_alert_to.split(",") if address.strip()
+        ]
+        channels.append(
+            EmailSmtpChannel(
+                host=settings.email_smtp_host,
+                port=settings.email_smtp_port,
+                sender=settings.email_alert_from,
+                recipients=recipients,
+                username=settings.email_smtp_username,
+                password=settings.email_smtp_password,
+                use_tls=settings.email_smtp_use_tls,
+            )
+        )
+
+    return channels
+
+
+def build_notifier_from_settings(settings: _AlertSettings) -> AlertNotifier:
+    severity = _as_alert_severity(settings.alert_min_severity)
+    channels = build_channels_from_settings(settings)
+    category_flags = {
+        "trade": settings.alert_on_trade_events,
+        "error": settings.alert_on_error_events,
+        "threshold": settings.alert_on_threshold_events,
+        "system": settings.alert_on_system_events,
+    }
+    return AlertNotifier(
+        channels,
+        enabled=settings.alerts_enabled,
+        min_severity=severity,
+        dedup_seconds=settings.alert_dedup_seconds,
+        category_flags=category_flags,
+    )

src/arbitrade/api/app.py

@@ -1,11 +1,19 @@
 from __future__ import annotations
 
+from collections.abc import AsyncIterator
+from contextlib import asynccontextmanager
+
 from fastapi import FastAPI
 
-from arbitrade.api.routes import router
+from arbitrade.alerting.notifier import build_notifier_from_settings
+from arbitrade.api.control_state import DashboardControlState
+from arbitrade.api.routes import public_router, router
 from arbitrade.config.settings import Settings
 from arbitrade.logging_setup import configure_logging
+from arbitrade.metrics import MetricsCalculator
+from arbitrade.runtime.lifecycle import graceful_shutdown, restore_runtime_state
 from arbitrade.storage.db import DuckDBStore
+from arbitrade.storage.repositories import AuditRepository, RuntimeStateRepository
 
 
 def create_app(settings: Settings) -> FastAPI:
@@ -14,6 +22,22 @@ def create_app(settings: Settings) -> FastAPI:
     db = DuckDBStore(settings)
     db.migrate()
 
-    app = FastAPI(title="arbitrade", version="0.1.0")
+    @asynccontextmanager
+    async def lifespan(app: FastAPI) -> AsyncIterator[None]:
+        await restore_runtime_state(app)
+        yield
+        await graceful_shutdown(app)
+
+    app = FastAPI(title="arbitrade", version="0.1.0", lifespan=lifespan)
+    app.state.settings = settings
+    app.state.store = db
+    app.state.metrics = MetricsCalculator(db)
+    app.state.audit_repository = AuditRepository(db)
+    app.state.runtime_state_repository = RuntimeStateRepository(db)
+    app.state.alert_notifier = build_notifier_from_settings(settings)
+    app.state.dashboard_controls = DashboardControlState(
+        is_running=not settings.kill_switch_active,
+    )
+    app.include_router(public_router)
     app.include_router(router)
     return app

src/arbitrade/api/auth.py

@@ -0,0 +1,38 @@
+from __future__ import annotations
+
+from secrets import compare_digest
+from typing import Annotated
+
+from fastapi import Depends, HTTPException, Request, status
+from fastapi.security import HTTPBasic, HTTPBasicCredentials
+
+dashboard_basic_auth = HTTPBasic(auto_error=False)
+
+
+def require_dashboard_auth(
+    request: Request,
+    credentials: Annotated[HTTPBasicCredentials | None, Depends(dashboard_basic_auth)],
+) -> None:
+    settings = request.app.state.settings
+    username = settings.dashboard_auth_username
+    password = settings.dashboard_auth_password
+
+    if username is None and password is None:
+        return
+
+    if username is None or password is None:
+        raise HTTPException(
+            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+            detail="Dashboard auth misconfigured",
+        )
+
+    if (
+        credentials is None
+        or not compare_digest(credentials.username, username)
+        or not compare_digest(credentials.password, password)
+    ):
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Not authenticated",
+            headers={"WWW-Authenticate": 'Basic realm="Arbitrade Dashboard"'},
+        )

src/arbitrade/api/control_state.py

@@ -0,0 +1,16 @@
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from datetime import UTC, datetime
+
+from arbitrade.risk.kill_switch import KillSwitch
+
+
+@dataclass(slots=True)
+class DashboardControlState:
+    is_running: bool = True
+    kill_switch: KillSwitch = field(default_factory=KillSwitch)
+    updated_at: datetime = field(default_factory=lambda: datetime.now(UTC))
+
+    def mark_updated(self) -> None:
+        self.updated_at = datetime.now(UTC)

src/arbitrade/api/routes.py

@@ -1,28 +1,599 @@
 from __future__ import annotations
 
+import json
+from collections.abc import AsyncIterator
 from datetime import UTC, datetime
+from pathlib import Path
+from typing import cast
+from urllib.parse import parse_qs
 
-from fastapi import APIRouter, Request
-from fastapi.responses import HTMLResponse, JSONResponse
+import duckdb
+from fastapi import APIRouter, Depends, Request
+from fastapi.responses import HTMLResponse, JSONResponse, StreamingResponse
 from fastapi.templating import Jinja2Templates
 
-router = APIRouter()
-templates = Jinja2Templates(directory="web/templates")
+from arbitrade.alerting.notifier import SupportsAlerts, SupportsAlertStatus
+from arbitrade.api.auth import require_dashboard_auth
+from arbitrade.api.control_state import DashboardControlState
+from arbitrade.storage.repositories import AuditRecord, AuditRepository
+
+router = APIRouter(dependencies=[Depends(require_dashboard_auth)])
+public_router = APIRouter()
+templates = Jinja2Templates(
+    directory=str(Path(__file__).resolve().parents[3] / "web" / "templates")
+)
 
 
-@router.get("/", response_class=HTMLResponse)
-async def home(request: Request) -> HTMLResponse:
+def _format_metric(value: float | None, *, precision: int = 2, suffix: str = "") -> str:
+    if value is None:
+        return "—"
+    return f"{value:.{precision}f}{suffix}"
+
+
+def _dashboard_metrics(request: Request) -> dict[str, str]:
+    metrics = request.app.state.metrics.compute()
+    return {
+        "realized_pnl": _format_metric(metrics.realized_pnl_usd, precision=2, suffix=" USD"),
+        "win_rate": _format_metric(
+            metrics.win_rate * 100.0 if metrics.win_rate is not None else None,
+            precision=1,
+            suffix="%",
+        ),
+        "avg_trade_duration": _format_metric(
+            metrics.avg_trade_duration_seconds, precision=1, suffix=" s"
+        ),
+        "opportunities_per_minute": _format_metric(
+            metrics.opportunities_per_minute, precision=1, suffix=" /min"
+        ),
+        "fill_rate": _format_metric(
+            metrics.fill_rate * 100.0 if metrics.fill_rate is not None else None,
+            precision=1,
+            suffix="%",
+        ),
+        "latency_p50": _format_metric(metrics.latency_p50_seconds, precision=3, suffix=" s"),
+        "latency_p95": _format_metric(metrics.latency_p95_seconds, precision=3, suffix=" s"),
+        "latency_p99": _format_metric(metrics.latency_p99_seconds, precision=3, suffix=" s"),
+        "generated_at": datetime.now(UTC).isoformat(),
+    }
+
+
+def _table_columns(conn: duckdb.DuckDBPyConnection, table_name: str) -> set[str]:
+    rows = conn.execute(f"PRAGMA table_info('{table_name}')").fetchall()
+    return {str(row[1]) for row in rows}
+
+
+def _dashboard_overview(request: Request) -> dict[str, object]:
+    store = request.app.state.store
+    with store.connect() as conn:
+        trade_columns = _table_columns(conn, "trades")
+        trade_ref_expr = "trade_ref" if "trade_ref" in trade_columns else "CAST(id AS VARCHAR)"
+        cycle_expr = "cycle" if "cycle" in trade_columns else "NULL"
+        if "finished_at" in trade_columns:
+            open_trade_filter = "finished_at IS NULL"
+        else:
+            open_trade_filter = "LOWER(status) NOT IN ('filled', 'closed', 'cancelled', 'canceled')"
+
+        portfolio_row = conn.execute("""
+            SELECT balances, total_value_usd
+            FROM portfolio_snapshots
+            ORDER BY snapshot_at DESC
+            LIMIT 1
+            """).fetchone()
+        open_trades = conn.execute(f"""
+            SELECT {trade_ref_expr}, status, started_at, {cycle_expr}
+            FROM trades
+            WHERE {open_trade_filter}
+            ORDER BY started_at DESC
+            LIMIT 5
+            """).fetchall()
+        pnl_total_row = conn.execute("""
+            SELECT COALESCE(SUM(COALESCE(realized_pnl, 0)), 0)
+            FROM trades
+            """).fetchone()
+        latest_opportunities = conn.execute("""
+            SELECT cycle, net_pct, est_profit, detected_at
+            FROM opportunities
+            ORDER BY detected_at DESC
+            LIMIT 5
+            """).fetchall()
+
+    balances_value = "—"
+    total_value = "—"
+    if portfolio_row is not None:
+        balances_raw, total_value_raw = portfolio_row
+        balances_value = str(balances_raw) if balances_raw is not None else "—"
+        if total_value_raw is not None:
+            total_value = f"{float(total_value_raw):.2f} USD"
+
+    open_trade_rows = [
+        {
+            "trade_ref": str(row[0]),
+            "status": str(row[1]),
+            "started_at": row[2].isoformat() if isinstance(row[2], datetime) else "—",
+            "cycle": str(row[3]) if row[3] is not None else "—",
+        }
+        for row in open_trades
+    ]
+    opportunity_rows = [
+        {
+            "cycle": str(row[0]),
+            "net_pct": f"{float(row[1]):.2f}%" if row[1] is not None else "—",
+            "est_profit": f"{float(row[2]):.2f} USD" if row[2] is not None else "—",
+            "detected_at": row[3].isoformat() if isinstance(row[3], datetime) else "—",
+        }
+        for row in latest_opportunities
+    ]
+
+    return {
+        "status": "live",
+        "generated_at": datetime.now(UTC).isoformat(),
+        "balances": balances_value,
+        "total_value": total_value,
+        "open_trade_count": len(open_trade_rows),
+        "open_trades": open_trade_rows,
+        "realized_pnl_total": f"{float(pnl_total_row[0]):.2f} USD" if pnl_total_row else "—",
+        "opportunities": opportunity_rows,
+    }
+
+
+def _dashboard_charts(request: Request) -> dict[str, object]:
+    store = request.app.state.store
+    with store.connect() as conn:
+        opportunity_rows = conn.execute("""
+            SELECT detected_at, cycle, net_pct, est_profit
+            FROM opportunities
+            ORDER BY detected_at DESC
+            LIMIT 10
+            """).fetchall()
+
+    chart_rows = list(reversed(opportunity_rows))
+    labels = [
+        row[0].isoformat() if isinstance(row[0], datetime) else f"opportunity-{index + 1}"
+        for index, row in enumerate(chart_rows)
+    ]
+    net_pct_values = [float(row[2]) if row[2] is not None else 0.0 for row in chart_rows]
+    est_profit_values = [float(row[3]) if row[3] is not None else 0.0 for row in chart_rows]
+    cycles = [str(row[1]) for row in chart_rows]
+
+    return {
+        "labels": labels,
+        "net_pct_values": net_pct_values,
+        "est_profit_values": est_profit_values,
+        "cycles": cycles,
+        "has_chart_data": bool(chart_rows),
+        "generated_at": datetime.now(UTC).isoformat(),
+    }
+
+
+def _dashboard_controls_state(request: Request) -> DashboardControlState:
+    return cast(DashboardControlState, request.app.state.dashboard_controls)
+
+
+def _audit_repository(request: Request) -> AuditRepository | None:
+    repository = getattr(request.app.state, "audit_repository", None)
+    return cast(AuditRepository | None, repository)
+
+
+def _record_audit(
+    request: Request,
+    *,
+    actor: str,
+    event_type: str,
+    decision: str,
+    payload: dict[str, object] | None = None,
+) -> None:
+    repository = _audit_repository(request)
+    if repository is None:
+        return
+    correlation_id = request.headers.get("x-request-id")
+    repository.insert(
+        AuditRecord(
+            occurred_at=datetime.now(UTC),
+            actor=actor,
+            event_type=event_type,
+            decision=decision,
+            payload=None if payload is None else {str(key): payload[key] for key in payload},
+            correlation_id=correlation_id,
+        )
+    )
+
+
+def _dashboard_audit(request: Request, *, limit: int = 15) -> dict[str, object]:
+    repository = _audit_repository(request)
+    if repository is None:
+        return {
+            "entries": [],
+            "generated_at": datetime.now(UTC).isoformat(),
+        }
+
+    records = repository.list_recent(limit=limit)
+    entries: list[dict[str, str]] = []
+    for record in records:
+        payload_text = "—"
+        if record.payload:
+            payload_text = json.dumps(record.payload)
+        entries.append(
+            {
+                "occurred_at": record.occurred_at.isoformat(),
+                "actor": record.actor,
+                "event_type": record.event_type,
+                "decision": record.decision,
+                "payload": payload_text,
+                "correlation_id": record.correlation_id or "—",
+            }
+        )
+
+    return {
+        "entries": entries,
+        "generated_at": datetime.now(UTC).isoformat(),
+    }
+
+
+def _alert_notifier(request: Request) -> SupportsAlerts | None:
+    notifier = getattr(request.app.state, "alert_notifier", None)
+    return cast(SupportsAlerts | None, notifier)
+
+
+def _alert_status_snapshot(request: Request) -> dict[str, object]:
+    notifier = getattr(request.app.state, "alert_notifier", None)
+    if isinstance(notifier, SupportsAlertStatus):
+        return notifier.status_snapshot()
+    return {
+        "enabled": False,
+        "has_channels": False,
+        "configured_channels": [],
+        "min_severity": "—",
+        "dedup_seconds": 0.0,
+        "last_result": "unavailable",
+        "last_attempted_at": None,
+        "last_success_at": None,
+        "last_error": None,
+        "last_event": None,
+        "last_channel_results": [],
+    }
+
+
+def _dashboard_controls(request: Request) -> dict[str, object]:
+    controls = _dashboard_controls_state(request)
+    settings = request.app.state.settings
+    alert_status = _alert_status_snapshot(request)
+    last_event = alert_status.get("last_event")
+    last_event_title = "—"
+    if isinstance(last_event, dict):
+        title_value = last_event.get("title")
+        if isinstance(title_value, str):
+            last_event_title = title_value
+
+    configured_channels = alert_status.get("configured_channels")
+    channels_display = "—"
+    if isinstance(configured_channels, list) and configured_channels:
+        channels_display = ", ".join(str(channel) for channel in configured_channels)
+
+    dedup_seconds_raw = alert_status.get("dedup_seconds", 0.0)
+    dedup_seconds = float(dedup_seconds_raw) if isinstance(dedup_seconds_raw, int | float) else 0.0
+
+    return {
+        "execution_status": "running" if controls.is_running else "stopped",
+        "kill_switch_status": "active" if controls.kill_switch.is_active else "inactive",
+        "kill_switch_reason": controls.kill_switch.reason or "—",
+        "paper_trading_mode": "enabled" if settings.paper_trading_mode else "disabled",
+        "trade_capital_usd": f"{float(settings.trade_capital_usd):.2f} USD",
+        "trade_capital_usd_value": f"{float(settings.trade_capital_usd):.2f}",
+        "max_trade_capital_usd": (
+            "—"
+            if settings.max_trade_capital_usd is None
+            else f"{float(settings.max_trade_capital_usd):.2f} USD"
+        ),
+        "max_trade_capital_usd_value": (
+            ""
+            if settings.max_trade_capital_usd is None
+            else f"{float(settings.max_trade_capital_usd):.2f}"
+        ),
+        "max_concurrent_trades": (
+            "—" if settings.max_concurrent_trades is None else str(settings.max_concurrent_trades)
+        ),
+        "max_concurrent_trades_value": (
+            "" if settings.max_concurrent_trades is None else str(settings.max_concurrent_trades)
+        ),
+        "alerts_enabled": "enabled" if bool(alert_status.get("enabled", False)) else "disabled",
+        "alerts_channels": channels_display,
+        "alerts_min_severity": str(alert_status.get("min_severity", "—")),
+        "alerts_dedup_seconds": f"{dedup_seconds:.0f}",
+        "alerts_last_result": str(alert_status.get("last_result", "unavailable")),
+        "alerts_last_attempted_at": str(alert_status.get("last_attempted_at") or "—"),
+        "alerts_last_success_at": str(alert_status.get("last_success_at") or "—"),
+        "alerts_last_event_title": last_event_title,
+        "alerts_last_error": str(alert_status.get("last_error") or "—"),
+        "alerts_last_channel_results": [
+            str(item) for item in cast(list[object], alert_status.get("last_channel_results", []))
+        ],
+        "updated_at": controls.updated_at.isoformat(),
+        "start_endpoint": "/dashboard/control/start",
+        "stop_endpoint": "/dashboard/control/stop",
+        "kill_switch_endpoint": "/dashboard/control/kill-switch",
+        "config_endpoint": "/dashboard/control/config",
+        "chart_endpoint": "/dashboard/fragment/charts",
+    }
+
+
+def _parse_form_body(body: bytes) -> dict[str, str]:
+    parsed = parse_qs(body.decode("utf-8"), keep_blank_values=True)
+    return {key: values[-1] for key, values in parsed.items() if values}
+
+
+def _form_bool(value: str | None) -> bool:
+    if value is None:
+        return False
+    return value.lower() in {"1", "true", "yes", "on"}
+
+
+async def _dashboard_response(
+    request: Request, template_name: str = "dashboard.html"
+) -> HTMLResponse:
     return templates.TemplateResponse(
         request=request,
-        name="health.html",
+        name=template_name,
         context={
-            "status": "ok",
-            "time": datetime.now(UTC).isoformat(),
-            "title": "Arbitrade Health",
+            "title": "Arbitrade Dashboard",
+            "request": request,
+            "metrics_endpoint": "/dashboard/fragment/metrics",
+            "overview_endpoint": "/dashboard/fragment/overview",
+            "controls_endpoint": "/dashboard/fragment/controls",
+            "charts_endpoint": "/dashboard/fragment/charts",
+            "audit_endpoint": "/dashboard/fragment/audit",
+            "stream_endpoint": "/dashboard/stream/metrics",
+            "overview_stream_endpoint": "/dashboard/stream/overview",
         },
     )
 
 
-@router.get("/health", response_class=JSONResponse)
+@router.get("/", response_class=HTMLResponse)
+async def home(request: Request) -> HTMLResponse:
+    return await _dashboard_response(request)
+
+
+@router.get("/dashboard", response_class=HTMLResponse)
+async def dashboard(request: Request) -> HTMLResponse:
+    return await _dashboard_response(request)
+
+
+@router.get("/dashboard/fragment/metrics", response_class=HTMLResponse)
+async def dashboard_metrics(request: Request) -> HTMLResponse:
+    return templates.TemplateResponse(
+        request=request,
+        name="partials/metrics.html",
+        context={"request": request, **_dashboard_metrics(request)},
+    )
+
+
+@router.get("/dashboard/fragment/overview", response_class=HTMLResponse)
+async def dashboard_overview(request: Request) -> HTMLResponse:
+    return templates.TemplateResponse(
+        request=request,
+        name="partials/overview.html",
+        context={"request": request, **_dashboard_overview(request)},
+    )
+
+
+@router.get("/dashboard/fragment/controls", response_class=HTMLResponse)
+async def dashboard_controls(request: Request) -> HTMLResponse:
+    return templates.TemplateResponse(
+        request=request,
+        name="partials/controls.html",
+        context={"request": request, **_dashboard_controls(request)},
+    )
+
+
+@router.get("/dashboard/fragment/charts", response_class=HTMLResponse)
+async def dashboard_charts(request: Request) -> HTMLResponse:
+    return templates.TemplateResponse(
+        request=request,
+        name="partials/charts.html",
+        context={"request": request, **_dashboard_charts(request)},
+    )
+
+
+@router.get("/dashboard/fragment/audit", response_class=HTMLResponse)
+async def dashboard_audit(request: Request) -> HTMLResponse:
+    return templates.TemplateResponse(
+        request=request,
+        name="partials/audit.html",
+        context={"request": request, **_dashboard_audit(request)},
+    )
+
+
+@router.get("/dashboard/api/alerts/status", response_class=JSONResponse)
+async def dashboard_alert_status(request: Request) -> JSONResponse:
+    return JSONResponse(_alert_status_snapshot(request))
+
+
+@router.get("/dashboard/api/audit/recent", response_class=JSONResponse)
+async def dashboard_audit_recent(request: Request) -> JSONResponse:
+    return JSONResponse(_dashboard_audit(request, limit=25))
+
+
+@router.post("/dashboard/control/start", response_class=HTMLResponse)
+async def dashboard_control_start(request: Request) -> HTMLResponse:
+    controls = _dashboard_controls_state(request)
+    controls.is_running = True
+    controls.mark_updated()
+    notifier = _alert_notifier(request)
+    if notifier is not None:
+        await notifier.notify(
+            category="system",
+            severity="info",
+            title="Execution started",
+            message="Dashboard control started execution.",
+        )
+    _record_audit(
+        request,
+        actor="dashboard_user",
+        event_type="dashboard.control.start",
+        decision="approved",
+        payload={"execution_status": "running"},
+    )
+    return templates.TemplateResponse(
+        request=request,
+        name="partials/controls.html",
+        context={"request": request, **_dashboard_controls(request)},
+    )
+
+
+@router.post("/dashboard/control/stop", response_class=HTMLResponse)
+async def dashboard_control_stop(request: Request) -> HTMLResponse:
+    controls = _dashboard_controls_state(request)
+    controls.is_running = False
+    controls.mark_updated()
+    notifier = _alert_notifier(request)
+    if notifier is not None:
+        await notifier.notify(
+            category="system",
+            severity="warning",
+            title="Execution stopped",
+            message="Dashboard control stopped execution.",
+        )
+    _record_audit(
+        request,
+        actor="dashboard_user",
+        event_type="dashboard.control.stop",
+        decision="approved",
+        payload={"execution_status": "stopped"},
+    )
+    return templates.TemplateResponse(
+        request=request,
+        name="partials/controls.html",
+        context={"request": request, **_dashboard_controls(request)},
+    )
+
+
+@router.post("/dashboard/control/kill-switch", response_class=HTMLResponse)
+async def dashboard_control_kill_switch(request: Request) -> HTMLResponse:
+    controls = _dashboard_controls_state(request)
+    form = _parse_form_body(await request.body())
+    reason = form.get("reason") or "manual"
+    controls.kill_switch.activate(reason=reason)
+    controls.is_running = False
+    controls.mark_updated()
+    notifier = _alert_notifier(request)
+    if notifier is not None:
+        await notifier.notify(
+            category="threshold",
+            severity="critical",
+            title="Kill switch activated",
+            message="Kill switch triggered from dashboard control.",
+            details={"reason": reason},
+        )
+    _record_audit(
+        request,
+        actor="dashboard_user",
+        event_type="dashboard.control.kill_switch",
+        decision="approved",
+        payload={"reason": reason},
+    )
+    return templates.TemplateResponse(
+        request=request,
+        name="partials/controls.html",
+        context={"request": request, **_dashboard_controls(request)},
+    )
+
+
+@router.post("/dashboard/control/config", response_class=HTMLResponse)
+async def dashboard_control_config(request: Request) -> HTMLResponse:
+    controls = _dashboard_controls_state(request)
+    settings = request.app.state.settings
+    form = _parse_form_body(await request.body())
+
+    if "trade_capital_usd" in form and form["trade_capital_usd"]:
+        settings.trade_capital_usd = float(form["trade_capital_usd"])
+    if "max_trade_capital_usd" in form:
+        max_trade_capital_value = form["max_trade_capital_usd"].strip()
+        settings.max_trade_capital_usd = (
+            float(max_trade_capital_value) if max_trade_capital_value else None
+        )
+    if "max_concurrent_trades" in form:
+        max_concurrent_value = form["max_concurrent_trades"].strip()
+        settings.max_concurrent_trades = int(max_concurrent_value) if max_concurrent_value else None
+
+    settings.paper_trading_mode = _form_bool(form.get("paper_trading_mode"))
+    controls.mark_updated()
+
+    notifier = _alert_notifier(request)
+    if notifier is not None:
+        await notifier.notify(
+            category="system",
+            severity="info",
+            title="Runtime config updated",
+            message="Dashboard control updated runtime risk and execution settings.",
+            details={
+                "trade_capital_usd": f"{settings.trade_capital_usd}",
+                "max_trade_capital_usd": (
+                    "none"
+                    if settings.max_trade_capital_usd is None
+                    else f"{settings.max_trade_capital_usd}"
+                ),
+                "max_concurrent_trades": (
+                    "none"
+                    if settings.max_concurrent_trades is None
+                    else f"{settings.max_concurrent_trades}"
+                ),
+                "paper_trading_mode": "true" if settings.paper_trading_mode else "false",
+            },
+        )
+    _record_audit(
+        request,
+        actor="dashboard_user",
+        event_type="dashboard.control.config",
+        decision="approved",
+        payload={
+            "trade_capital_usd": settings.trade_capital_usd,
+            "max_trade_capital_usd": settings.max_trade_capital_usd,
+            "max_concurrent_trades": settings.max_concurrent_trades,
+            "paper_trading_mode": settings.paper_trading_mode,
+        },
+    )
+
+    return templates.TemplateResponse(
+        request=request,
+        name="partials/controls.html",
+        context={"request": request, **_dashboard_controls(request)},
+    )
+
+
+@router.get("/dashboard/stream/metrics")
+async def dashboard_metrics_stream(request: Request) -> StreamingResponse:
+    fragment = (
+        templates.get_template("partials/metrics.html")
+        .render(
+            request=request,
+            **_dashboard_metrics(request),
+        )
+        .strip()
+        .replace("\n", "")
+    )
+
+    async def _event_stream() -> AsyncIterator[bytes]:
+        payload = json.dumps(fragment)
+        yield f"event: metrics\ndata: {payload}\n\n".encode()
+
+    return StreamingResponse(_event_stream(), media_type="text/event-stream")
+
+
+@router.get("/dashboard/stream/overview")
+async def dashboard_overview_stream(request: Request) -> StreamingResponse:
+    fragment = (
+        templates.get_template("partials/overview.html")
+        .render(request=request, **_dashboard_overview(request))
+        .strip()
+        .replace("\n", "")
+    )
+
+    async def _event_stream() -> AsyncIterator[bytes]:
+        payload = json.dumps(fragment)
+        yield f"event: overview\ndata: {payload}\n\n".encode()
+
+    return StreamingResponse(_event_stream(), media_type="text/event-stream")
+
+
+@public_router.get("/health", response_class=JSONResponse)
 async def health() -> JSONResponse:
     return JSONResponse({"status": "ok", "service": "arbitrade"})

src/arbitrade/config/settings.py

@@ -3,12 +3,17 @@ from __future__ import annotations
 from functools import lru_cache
 from pathlib import Path
 
-from pydantic import Field
+from pydantic import Field, field_validator, model_validator
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
 
 class Settings(BaseSettings):
-    model_config = SettingsConfigDict(env_file=".env", env_file_encoding="utf-8", extra="ignore")
+    model_config = SettingsConfigDict(
+        env_file=".env",
+        env_file_encoding="utf-8",
+        extra="ignore",
+        env_ignore_empty=True,
+    )
 
     app_env: str = Field(default="dev", alias="APP_ENV")
     app_host: str = Field(default="0.0.0.0", alias="APP_HOST")
@@ -17,10 +22,125 @@ class Settings(BaseSettings):
     log_level: str = Field(default="INFO", alias="LOG_LEVEL")
     log_json: bool = Field(default=True, alias="LOG_JSON")
 
+    dashboard_auth_username: str | None = Field(
+        default=None,
+        alias="DASHBOARD_AUTH_USERNAME",
+    )
+    dashboard_auth_password: str | None = Field(
+        default=None,
+        alias="DASHBOARD_AUTH_PASSWORD",
+    )
+
+    alerts_enabled: bool = Field(default=True, alias="ALERTS_ENABLED")
+    alert_min_severity: str = Field(default="warning", alias="ALERT_MIN_SEVERITY")
+    alert_dedup_seconds: float = Field(default=30.0, alias="ALERT_DEDUP_SECONDS")
+    alert_on_trade_events: bool = Field(default=True, alias="ALERT_ON_TRADE_EVENTS")
+    alert_on_error_events: bool = Field(default=True, alias="ALERT_ON_ERROR_EVENTS")
+    alert_on_threshold_events: bool = Field(default=True, alias="ALERT_ON_THRESHOLD_EVENTS")
+    alert_on_system_events: bool = Field(default=True, alias="ALERT_ON_SYSTEM_EVENTS")
+
+    telegram_alerts_enabled: bool = Field(default=False, alias="TELEGRAM_ALERTS_ENABLED")
+    telegram_bot_token: str | None = Field(default=None, alias="TELEGRAM_BOT_TOKEN")
+    telegram_chat_id: str | None = Field(default=None, alias="TELEGRAM_CHAT_ID")
+
+    discord_alerts_enabled: bool = Field(default=False, alias="DISCORD_ALERTS_ENABLED")
+    discord_webhook_url: str | None = Field(default=None, alias="DISCORD_WEBHOOK_URL")
+
+    email_alerts_enabled: bool = Field(default=False, alias="EMAIL_ALERTS_ENABLED")
+    email_smtp_host: str | None = Field(default=None, alias="EMAIL_SMTP_HOST")
+    email_smtp_port: int = Field(default=587, alias="EMAIL_SMTP_PORT")
+    email_smtp_username: str | None = Field(default=None, alias="EMAIL_SMTP_USERNAME")
+    email_smtp_password: str | None = Field(default=None, alias="EMAIL_SMTP_PASSWORD")
+    email_alert_from: str | None = Field(default=None, alias="EMAIL_ALERT_FROM")
+    email_alert_to: str | None = Field(default=None, alias="EMAIL_ALERT_TO")
+    email_smtp_use_tls: bool = Field(default=True, alias="EMAIL_SMTP_USE_TLS")
+
     duckdb_path: Path = Field(default=Path("./data/arbitrade.duckdb"), alias="DUCKDB_PATH")
 
+    kraken_rest_url: str = Field(default="https://api.kraken.com", alias="KRAKEN_REST_URL")
+    kraken_ws_url: str = Field(default="wss://ws.kraken.com/v2", alias="KRAKEN_WS_URL")
+    kraken_private_rate_limit_seconds: float = Field(
+        default=1.0, alias="KRAKEN_PRIVATE_RATE_LIMIT_SECONDS"
+    )
+    kraken_http_timeout_seconds: float = Field(default=10.0, alias="KRAKEN_HTTP_TIMEOUT_SECONDS")
+    kraken_retry_attempts: int = Field(default=3, alias="KRAKEN_RETRY_ATTEMPTS")
+    kraken_retry_base_delay_seconds: float = Field(
+        default=0.25, alias="KRAKEN_RETRY_BASE_DELAY_SECONDS"
+    )
+    kraken_api_key: str | None = Field(default=None, alias="KRAKEN_API_KEY")
+    kraken_api_secret: str | None = Field(default=None, alias="KRAKEN_API_SECRET")
+    kraken_api_key_permissions: str = Field(
+        default="query,trade",
+        alias="KRAKEN_API_KEY_PERMISSIONS",
+    )
+    ws_heartbeat_timeout_seconds: float = Field(default=20.0, alias="WS_HEARTBEAT_TIMEOUT_SECONDS")
+    ws_max_staleness_seconds: float = Field(default=5.0, alias="WS_MAX_STALENESS_SECONDS")
+    paper_trading_mode: bool = Field(default=True, alias="PAPER_TRADING_MODE")
+    trade_capital_usd: float = Field(default=100.0, alias="TRADE_CAPITAL_USD")
+    max_trade_capital_usd: float = Field(default=100.0, alias="MAX_TRADE_CAPITAL_USD")
+    max_concurrent_trades: int | None = Field(default=None, alias="MAX_CONCURRENT_TRADES")
+    max_exposure_per_asset_usd: float | None = Field(
+        default=None,
+        alias="MAX_EXPOSURE_PER_ASSET_USD",
+    )
+    quote_balance_asset: str = Field(default="USD", alias="QUOTE_BALANCE_ASSET")
+    min_order_size_usd: float | None = Field(default=None, alias="MIN_ORDER_SIZE_USD")
+    kill_switch_active: bool = Field(default=False, alias="KILL_SWITCH_ACTIVE")
+    daily_loss_limit_usd: float | None = Field(default=None, alias="DAILY_LOSS_LIMIT_USD")
+    cumulative_loss_limit_usd: float | None = Field(default=None, alias="CUMULATIVE_LOSS_LIMIT_USD")
+    max_source_latency_ms: float | None = Field(default=None, alias="MAX_SOURCE_LATENCY_MS")
+    max_apply_latency_ms: float | None = Field(default=None, alias="MAX_APPLY_LATENCY_MS")
+    max_consecutive_failures: int | None = Field(default=None, alias="MAX_CONSECUTIVE_FAILURES")
+
     fernet_key: str | None = Field(default=None, alias="FERNET_KEY")
 
+    @field_validator("app_env")
+    @classmethod
+    def _validate_app_env(cls, value: str) -> str:
+        normalized = value.strip().lower()
+        if normalized not in {"dev", "test", "prod"}:
+            raise ValueError("APP_ENV must be one of: dev, test, prod")
+        return normalized
+
+    @field_validator("log_level")
+    @classmethod
+    def _validate_log_level(cls, value: str) -> str:
+        normalized = value.strip().upper()
+        if normalized not in {"DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"}:
+            raise ValueError("LOG_LEVEL must be one of: DEBUG, INFO, WARNING, ERROR, CRITICAL")
+        return normalized
+
+    @field_validator("alert_min_severity")
+    @classmethod
+    def _validate_alert_severity(cls, value: str) -> str:
+        normalized = value.strip().lower()
+        if normalized not in {"info", "warning", "error", "critical"}:
+            raise ValueError("ALERT_MIN_SEVERITY must be one of: info, warning, error, critical")
+        return normalized
+
+    @model_validator(mode="after")
+    def _validate_security_constraints(self) -> Settings:
+        if bool(self.dashboard_auth_username) ^ bool(self.dashboard_auth_password):
+            raise ValueError("dashboard auth requires both username and password")
+
+        if bool(self.kraken_api_key) ^ bool(self.kraken_api_secret):
+            raise ValueError("Kraken API auth requires both API key and secret")
+
+        permissions = {
+            token.strip().lower()
+            for token in self.kraken_api_key_permissions.split(",")
+            if token.strip()
+        }
+        if permissions and ("query" not in permissions or "trade" not in permissions):
+            raise ValueError("KRAKEN_API_KEY_PERMISSIONS must include query and trade")
+        if "withdraw" in permissions or "withdrawals" in permissions:
+            raise ValueError("KRAKEN_API_KEY_PERMISSIONS must not include withdrawal scope")
+
+        if self.alert_dedup_seconds < 0.0:
+            raise ValueError("ALERT_DEDUP_SECONDS must be >= 0")
+
+        return self
+
 
 @lru_cache(maxsize=1)
 def get_settings() -> Settings:

src/arbitrade/detection/__init__.py

@@ -0,0 +1,12 @@
+"""Arbitrage detection package."""
+
+from arbitrade.detection.engine import CycleScore, IncrementalCycleDetector, OpportunityEvent
+from arbitrade.detection.graph import CurrencyGraph, TriangularCycle
+
+__all__ = [
+    "CurrencyGraph",
+    "TriangularCycle",
+    "CycleScore",
+    "OpportunityEvent",
+    "IncrementalCycleDetector",
+]

src/arbitrade/detection/benchmark.py

@@ -0,0 +1,113 @@
+from __future__ import annotations
+
+import argparse
+import statistics
+import time
+from dataclasses import asdict, dataclass
+
+import orjson
+
+from arbitrade.detection.engine import IncrementalCycleDetector
+from arbitrade.detection.graph import CurrencyGraph
+from arbitrade.exchange.models import BookLevel
+from arbitrade.market_data.order_book import OrderBook
+
+
+@dataclass(frozen=True, slots=True)
+class DetectionBenchmarkResult:
+    iterations: int
+    total_ms: float
+    avg_ms: float
+    p50_ms: float
+    p95_ms: float
+    max_ms: float
+    target_ms: float
+
+    @property
+    def meets_target(self) -> bool:
+        return self.p95_ms <= self.target_ms
+
+
+def _make_book(*, bid: float, ask: float) -> OrderBook:
+    book = OrderBook()
+    book.apply_bids([BookLevel(price=bid, volume=10.0)])
+    book.apply_asks([BookLevel(price=ask, volume=10.0)])
+    return book
+
+
+def _build_detector_and_books() -> tuple[IncrementalCycleDetector, dict[str, OrderBook]]:
+    asset_pairs = {
+        "XXBTZUSD": {"wsname": "BTC/USD"},
+        "XETHXXBT": {"wsname": "ETH/BTC"},
+        "XETHZUSD": {"wsname": "ETH/USD"},
+    }
+    graph = CurrencyGraph.from_kraken_asset_pairs(asset_pairs)
+    cycles = graph.triangular_cycles()
+    index = graph.index_cycles_by_pair(cycles)
+
+    detector = IncrementalCycleDetector(
+        index,
+        fee_rate=0.001,
+        min_profit_threshold=0.001,
+        max_depth_levels=5,
+        max_book_age_seconds=10.0,
+    )
+
+    books = {
+        "BTC/USD": _make_book(bid=99.9, ask=100.0),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.2, ask=5.21),
+    }
+    return detector, books
+
+
+def run_incremental_detection_benchmark(
+    *,
+    iterations: int = 50_000,
+    target_ms: float = 1.0,
+) -> DetectionBenchmarkResult:
+    if iterations <= 0:
+        raise ValueError("iterations must be > 0")
+
+    detector, books = _build_detector_and_books()
+
+    samples_ms: list[float] = []
+    started_ns = time.perf_counter_ns()
+    for _ in range(iterations):
+        t0_ns = time.perf_counter_ns()
+        detector.score_updated_pair("ETH/BTC", books)
+        elapsed_ms = (time.perf_counter_ns() - t0_ns) / 1_000_000
+        samples_ms.append(elapsed_ms)
+
+    total_ms = (time.perf_counter_ns() - started_ns) / 1_000_000
+    return DetectionBenchmarkResult(
+        iterations=iterations,
+        total_ms=total_ms,
+        avg_ms=statistics.fmean(samples_ms),
+        p50_ms=statistics.quantiles(samples_ms, n=100)[49],
+        p95_ms=statistics.quantiles(samples_ms, n=100)[94],
+        max_ms=max(samples_ms),
+        target_ms=target_ms,
+    )
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="Benchmark incremental detection latency")
+    parser.add_argument("--iterations", type=int, default=50_000)
+    parser.add_argument("--target-ms", type=float, default=1.0)
+    args = parser.parse_args()
+
+    result = run_incremental_detection_benchmark(
+        iterations=args.iterations,
+        target_ms=args.target_ms,
+    )
+
+    payload = {
+        **asdict(result),
+        "meets_target": result.meets_target,
+    }
+    print(orjson.dumps(payload).decode("utf-8"))
+
+
+if __name__ == "__main__":
+    main()

src/arbitrade/detection/engine.py

@@ -0,0 +1,295 @@
+from __future__ import annotations
+
+from collections.abc import Mapping
+from dataclasses import dataclass
+from datetime import UTC, datetime
+
+from arbitrade.detection.graph import TriangularCycle
+from arbitrade.exchange.models import BookLevel
+from arbitrade.market_data.order_book import OrderBook
+
+
+def _normalize_pair_symbol(symbol: str) -> str:
+    if "/" not in symbol:
+        return symbol.upper()
+
+    base, quote = symbol.split("/", 1)
+    return f"{base.upper()}/{quote.upper()}"
+
+
+@dataclass(frozen=True, slots=True)
+class CycleScore:
+    cycle: TriangularCycle
+    gross_rate: float
+    net_rate: float
+    min_profit_threshold: float
+    updated_pair: str
+    scored_at: datetime
+
+    @property
+    def is_profitable(self) -> bool:
+        return (self.net_rate - 1.0) >= self.min_profit_threshold
+
+
+@dataclass(frozen=True, slots=True)
+class OpportunityEvent:
+    detected_at: datetime
+    cycle: str
+    updated_pair: str
+    gross_rate: float
+    net_rate: float
+    gross_pct: float
+    net_pct: float
+    est_profit: float
+    allocated_capital: float = 1.0
+
+    @classmethod
+    def from_cycle_score(cls, score: CycleScore, base_capital: float = 1.0) -> OpportunityEvent:
+        gross_pct = (score.gross_rate - 1.0) * 100.0
+        net_pct = (score.net_rate - 1.0) * 100.0
+        est_profit = (score.net_rate - 1.0) * base_capital
+        a, b, c = score.cycle.currencies
+        cycle = f"{a}->{b}->{c}->{a}"
+        return cls(
+            detected_at=score.scored_at,
+            cycle=cycle,
+            updated_pair=score.updated_pair,
+            gross_rate=score.gross_rate,
+            net_rate=score.net_rate,
+            gross_pct=gross_pct,
+            net_pct=net_pct,
+            est_profit=est_profit,
+            allocated_capital=base_capital,
+        )
+
+
+class IncrementalCycleDetector:
+    def __init__(
+        self,
+        cycles_by_pair: Mapping[str, list[TriangularCycle]],
+        *,
+        fee_rate: float = 0.0,
+        max_depth_levels: int = 10,
+        min_profit_threshold: float = 0.0,
+        min_order_size_by_pair: Mapping[str, float] | None = None,
+        max_book_age_seconds: float | None = None,
+    ) -> None:
+        self._cycles_by_pair = {
+            _normalize_pair_symbol(pair): list(cycles) for pair, cycles in cycles_by_pair.items()
+        }
+        self._fee_multiplier = 1.0 - fee_rate
+        self._max_depth_levels = max_depth_levels
+        self._min_profit_threshold = min_profit_threshold
+        self._max_book_age_seconds = max_book_age_seconds
+        self._min_order_size_by_pair = {
+            _normalize_pair_symbol(pair): float(min_size)
+            for pair, min_size in (min_order_size_by_pair or {}).items()
+        }
+
+        if self._fee_multiplier < 0.0:
+            raise ValueError("fee_rate must be <= 1.0")
+        if self._max_depth_levels <= 0:
+            raise ValueError("max_depth_levels must be > 0")
+        if self._min_profit_threshold < 0.0:
+            raise ValueError("min_profit_threshold must be >= 0.0")
+        if self._max_book_age_seconds is not None and self._max_book_age_seconds <= 0.0:
+            raise ValueError("max_book_age_seconds must be > 0.0")
+        for min_size in self._min_order_size_by_pair.values():
+            if min_size <= 0.0:
+                raise ValueError("minimum order size must be > 0.0")
+
+    def score_updated_pair(
+        self,
+        updated_pair: str,
+        books: Mapping[str, OrderBook],
+    ) -> list[CycleScore]:
+        normalized_pair = _normalize_pair_symbol(updated_pair)
+        impacted_cycles = self._cycles_by_pair.get(normalized_pair, [])
+
+        normalized_books = {_normalize_pair_symbol(symbol): book for symbol, book in books.items()}
+
+        scores: list[CycleScore] = []
+        scored_at = datetime.now(UTC)
+        for cycle in impacted_cycles:
+            rates = self._score_cycle(cycle, normalized_books, scored_at)
+            if rates is None:
+                continue
+            gross_rate, net_rate = rates
+            if (net_rate - 1.0) < self._min_profit_threshold:
+                continue
+            scores.append(
+                CycleScore(
+                    cycle=cycle,
+                    gross_rate=gross_rate,
+                    net_rate=net_rate,
+                    min_profit_threshold=self._min_profit_threshold,
+                    updated_pair=normalized_pair,
+                    scored_at=scored_at,
+                )
+            )
+
+        return scores
+
+    def opportunities_for_updated_pair(
+        self,
+        updated_pair: str,
+        books: Mapping[str, OrderBook],
+        *,
+        base_capital: float = 1.0,
+    ) -> list[OpportunityEvent]:
+        if base_capital <= 0.0:
+            raise ValueError("base_capital must be > 0.0")
+
+        scores = self.score_updated_pair(updated_pair, books)
+        return [OpportunityEvent.from_cycle_score(score, base_capital) for score in scores]
+
+    def _score_cycle(
+        self,
+        cycle: TriangularCycle,
+        books: Mapping[str, OrderBook],
+        scored_at: datetime,
+    ) -> tuple[float, float] | None:
+        if not self._is_cycle_fresh(cycle, books, scored_at):
+            return None
+
+        a, b, c = cycle.currencies
+        gross_amount = 1.0
+
+        gross_ab = self._convert(gross_amount, a, b, cycle, books)
+        if gross_ab is None:
+            return None
+        net_ab = gross_ab * self._fee_multiplier
+
+        gross_bc = self._convert(gross_ab, b, c, cycle, books)
+        if gross_bc is None:
+            return None
+        net_bc = self._convert(net_ab, b, c, cycle, books)
+        if net_bc is None:
+            return None
+        net_bc *= self._fee_multiplier
+
+        gross_ca = self._convert(gross_bc, c, a, cycle, books)
+        if gross_ca is None:
+            return None
+        net_ca = self._convert(net_bc, c, a, cycle, books)
+        if net_ca is None:
+            return None
+        net_ca *= self._fee_multiplier
+
+        return gross_ca, net_ca
+
+    def _is_cycle_fresh(
+        self,
+        cycle: TriangularCycle,
+        books: Mapping[str, OrderBook],
+        scored_at: datetime,
+    ) -> bool:
+        if self._max_book_age_seconds is None:
+            return True
+
+        for pair in cycle.pairs:
+            normalized_pair = _normalize_pair_symbol(pair)
+            book = books.get(normalized_pair)
+            if book is None:
+                return False
+
+            age_seconds = (scored_at - book.updated_at).total_seconds()
+            if age_seconds > self._max_book_age_seconds:
+                return False
+
+        return True
+
+    @staticmethod
+    def _pair_for_edge(cycle: TriangularCycle, from_currency: str, to_currency: str) -> str | None:
+        for pair in cycle.pairs:
+            if "/" not in pair:
+                continue
+            base, quote = pair.split("/", 1)
+            base = base.upper()
+            quote = quote.upper()
+            if {base, quote} == {from_currency, to_currency}:
+                return f"{base}/{quote}"
+        return None
+
+    def _convert(
+        self,
+        amount: float,
+        from_currency: str,
+        to_currency: str,
+        cycle: TriangularCycle,
+        books: Mapping[str, OrderBook],
+    ) -> float | None:
+        pair = self._pair_for_edge(cycle, from_currency, to_currency)
+        if pair is None:
+            return None
+
+        book = books.get(pair)
+        if book is None:
+            return None
+
+        bids, asks = book.top_levels(depth=self._max_depth_levels)
+
+        base, quote = pair.split("/", 1)
+        base = base.upper()
+        quote = quote.upper()
+
+        if from_currency == base and to_currency == quote:
+            quote_out = self._sell_base_for_quote(amount, bids)
+            if quote_out is None:
+                return None
+            if not self._is_min_order_size_satisfied(pair, amount):
+                return None
+            return quote_out
+
+        if from_currency == quote and to_currency == base:
+            base_out = self._buy_base_with_quote(amount, asks)
+            if base_out is None:
+                return None
+            if not self._is_min_order_size_satisfied(pair, base_out):
+                return None
+            return base_out
+
+        return None
+
+    def _is_min_order_size_satisfied(self, pair: str, base_amount: float) -> bool:
+        min_size = self._min_order_size_by_pair.get(pair)
+        if min_size is None:
+            return True
+        return base_amount >= min_size
+
+    @staticmethod
+    def _sell_base_for_quote(amount_base: float, bids: list[BookLevel]) -> float | None:
+        remaining = amount_base
+        quote_out = 0.0
+        for level in bids:
+            if remaining <= 0.0:
+                break
+            if level.price <= 0.0 or level.volume <= 0.0:
+                continue
+
+            executed = min(remaining, level.volume)
+            quote_out += executed * level.price
+            remaining -= executed
+
+        if remaining > 0.0:
+            return None
+        return quote_out
+
+    @staticmethod
+    def _buy_base_with_quote(amount_quote: float, asks: list[BookLevel]) -> float | None:
+        remaining_quote = amount_quote
+        base_out = 0.0
+        for level in asks:
+            if remaining_quote <= 0.0:
+                break
+            if level.price <= 0.0 or level.volume <= 0.0:
+                continue
+
+            level_quote_capacity = level.volume * level.price
+            spend = min(remaining_quote, level_quote_capacity)
+            base_out += spend / level.price
+            remaining_quote -= spend
+
+        if remaining_quote > 0.0:
+            return None
+        return base_out

src/arbitrade/detection/graph.py

@@ -0,0 +1,90 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Any
+
+
+@dataclass(frozen=True, slots=True)
+class TriangularCycle:
+    currencies: tuple[str, str, str]
+    pairs: tuple[str, str, str]
+
+
+def _canonical_pair(base: str, quote: str) -> str:
+    return f"{base}/{quote}"
+
+
+class CurrencyGraph:
+    def __init__(self) -> None:
+        self._adjacency: dict[str, set[str]] = {}
+        self._pair_by_direction: dict[tuple[str, str], str] = {}
+
+    @property
+    def adjacency(self) -> dict[str, set[str]]:
+        return self._adjacency
+
+    @property
+    def pair_by_direction(self) -> dict[tuple[str, str], str]:
+        return self._pair_by_direction
+
+    def add_pair(self, base: str, quote: str, pair_symbol: str | None = None) -> None:
+        normalized_base = base.upper()
+        normalized_quote = quote.upper()
+        symbol = pair_symbol or _canonical_pair(normalized_base, normalized_quote)
+
+        self._adjacency.setdefault(normalized_base, set()).add(normalized_quote)
+        self._adjacency.setdefault(normalized_quote, set()).add(normalized_base)
+
+        self._pair_by_direction[(normalized_base, normalized_quote)] = symbol
+        self._pair_by_direction[(normalized_quote, normalized_base)] = symbol
+
+    @classmethod
+    def from_kraken_asset_pairs(cls, asset_pairs: dict[str, Any]) -> CurrencyGraph:
+        graph = cls()
+        for value in asset_pairs.values():
+            if not isinstance(value, dict):
+                continue
+
+            wsname = value.get("wsname")
+            if isinstance(wsname, str) and "/" in wsname:
+                base, quote = wsname.split("/", 1)
+                graph.add_pair(base, quote, wsname)
+                continue
+
+            raw_base = value.get("base")
+            raw_quote = value.get("quote")
+            if isinstance(raw_base, str) and isinstance(raw_quote, str):
+                graph.add_pair(raw_base, raw_quote)
+
+        return graph
+
+    def triangular_cycles(self) -> list[TriangularCycle]:
+        found: dict[tuple[str, str, str], TriangularCycle] = {}
+
+        for a, neighbors_a in self._adjacency.items():
+            for b in neighbors_a:
+                if a >= b:
+                    continue
+                neighbors_b = self._adjacency.get(b, set())
+                for c in neighbors_b:
+                    if b >= c:
+                        continue
+                    if a not in self._adjacency.get(c, set()):
+                        continue
+
+                    p_ab = self._pair_by_direction[(a, b)]
+                    p_bc = self._pair_by_direction[(b, c)]
+                    p_ca = self._pair_by_direction[(c, a)]
+
+                    key = (a, b, c)
+                    found[key] = TriangularCycle(currencies=key, pairs=(p_ab, p_bc, p_ca))
+
+        return list(found.values())
+
+    @staticmethod
+    def index_cycles_by_pair(cycles: list[TriangularCycle]) -> dict[str, list[TriangularCycle]]:
+        index: dict[str, list[TriangularCycle]] = {}
+        for cycle in cycles:
+            for pair in cycle.pairs:
+                index.setdefault(pair, []).append(cycle)
+        return index

src/arbitrade/exchange/__init__.py

@@ -0,0 +1 @@
+"""Kraken exchange integration package."""

src/arbitrade/exchange/kraken_rest.py

@@ -0,0 +1,281 @@
+from __future__ import annotations
+
+import asyncio
+import time
+from typing import Any
+from urllib.parse import urlencode
+
+import httpx
+import structlog
+
+from arbitrade.config.settings import Settings
+from arbitrade.exchange.models import KrakenApiResult, LatencySample
+from arbitrade.exchange.signing import sign_kraken_private_path
+
+_LOG = structlog.get_logger(__name__)
+
+
+def _result_dict(payload: dict[str, Any]) -> dict[str, Any]:
+    result = payload.get("result", {})
+    if isinstance(result, dict):
+        return result
+    return {}
+
+
+class KrakenRestClient:
+    def __init__(self, settings: Settings) -> None:
+        self._settings = settings
+        self._client = httpx.AsyncClient(
+            base_url=settings.kraken_rest_url,
+            timeout=settings.kraken_http_timeout_seconds,
+            limits=httpx.Limits(max_keepalive_connections=10, max_connections=50),
+            headers={"User-Agent": "arbitrade/0.1.0"},
+        )
+        self._private_lock = asyncio.Lock()
+
+        issues = self.validate_compliance()
+        if issues:
+            _LOG.warning("kraken_compliance_issues", issues=issues)
+        else:
+            _LOG.info("kraken_compliance_ok")
+
+    def validate_compliance(self) -> list[str]:
+        issues: list[str] = []
+
+        if not self._settings.kraken_rest_url.startswith("https://"):
+            issues.append("KRAKEN_REST_URL should use https://")
+
+        if self._settings.kraken_private_rate_limit_seconds < 1.0:
+            issues.append("KRAKEN_PRIVATE_RATE_LIMIT_SECONDS below 1.0 may violate Kraken limits")
+
+        if self._settings.kraken_retry_attempts < 1:
+            issues.append("KRAKEN_RETRY_ATTEMPTS must be >= 1")
+
+        if self._settings.kraken_retry_base_delay_seconds < 0:
+            issues.append("KRAKEN_RETRY_BASE_DELAY_SECONDS must be >= 0")
+
+        return issues
+
+    async def close(self) -> None:
+        await self._client.aclose()
+
+    async def warm_connection_pool(self) -> None:
+        await self.server_time()
+
+    async def _request_with_retry(
+        self,
+        endpoint: str,
+        params: dict[str, Any] | None = None,
+    ) -> KrakenApiResult:
+        attempts = self._settings.kraken_retry_attempts
+        delay = self._settings.kraken_retry_base_delay_seconds
+        params = params or {}
+
+        for attempt in range(1, attempts + 1):
+            t0 = time.perf_counter()
+            try:
+                response = await self._client.get(endpoint, params=params)
+                response.raise_for_status()
+                payload = response.json()
+                if payload.get("error"):
+                    raise RuntimeError(f"Kraken error: {payload['error']}")
+
+                latency = (time.perf_counter() - t0) * 1000
+                _LOG.info(
+                    "kraken_rest_request_ok",
+                    endpoint=endpoint,
+                    attempt=attempt,
+                    latency_ms=latency,
+                    sample=LatencySample.now("rest_request", latency_ms=latency).latency_ms,
+                )
+                return KrakenApiResult(endpoint=endpoint, payload=payload)
+            except Exception as exc:
+                latency = (time.perf_counter() - t0) * 1000
+                _LOG.warning(
+                    "kraken_rest_request_failed",
+                    endpoint=endpoint,
+                    attempt=attempt,
+                    latency_ms=latency,
+                    error=str(exc),
+                )
+                if attempt >= attempts:
+                    raise
+                await asyncio.sleep(delay * (2 ** (attempt - 1)))
+
+        raise RuntimeError("unreachable retry loop")
+
+    async def _private_post_with_retry(
+        self,
+        endpoint: str,
+        data: dict[str, str] | None = None,
+    ) -> KrakenApiResult:
+        api_key = self._settings.kraken_api_key
+        api_secret = self._settings.kraken_api_secret
+        if not api_key or not api_secret:
+            raise RuntimeError("Missing Kraken API credentials for private endpoint")
+
+        attempts = self._settings.kraken_retry_attempts
+        delay = self._settings.kraken_retry_base_delay_seconds
+
+        for attempt in range(1, attempts + 1):
+            t0 = time.perf_counter()
+            try:
+                nonce = str(int(time.time() * 1000))
+                payload = {"nonce": nonce}
+                if data is not None:
+                    payload.update(data)
+
+                encoded = urlencode(payload)
+                signature = sign_kraken_private_path(endpoint, nonce, encoded, api_secret)
+
+                response = await self._client.post(
+                    endpoint,
+                    data=payload,
+                    headers={
+                        "API-Key": api_key,
+                        "API-Sign": signature,
+                    },
+                )
+                response.raise_for_status()
+                body = response.json()
+                if body.get("error"):
+                    raise RuntimeError(f"Kraken error: {body['error']}")
+
+                latency = (time.perf_counter() - t0) * 1000
+                _LOG.info(
+                    "kraken_private_rest_request_ok",
+                    endpoint=endpoint,
+                    attempt=attempt,
+                    latency_ms=latency,
+                    sample=LatencySample.now("private_rest_request", latency_ms=latency).latency_ms,
+                )
+                return KrakenApiResult(endpoint=endpoint, payload=body)
+            except Exception as exc:
+                latency = (time.perf_counter() - t0) * 1000
+                _LOG.warning(
+                    "kraken_private_rest_request_failed",
+                    endpoint=endpoint,
+                    attempt=attempt,
+                    latency_ms=latency,
+                    error=str(exc),
+                )
+                if attempt >= attempts:
+                    raise
+                await asyncio.sleep(delay * (2 ** (attempt - 1)))
+
+        raise RuntimeError("unreachable retry loop")
+
+    async def server_time(self) -> dict[str, Any]:
+        result = await self._request_with_retry("/0/public/Time")
+        return _result_dict(result.payload)
+
+    async def assets(self) -> dict[str, Any]:
+        result = await self._request_with_retry("/0/public/Assets")
+        return _result_dict(result.payload)
+
+    async def asset_pairs(self) -> dict[str, Any]:
+        result = await self._request_with_retry("/0/public/AssetPairs")
+        return _result_dict(result.payload)
+
+    async def _throttled_private_call(
+        self,
+        endpoint: str,
+        data: dict[str, str] | None = None,
+    ) -> dict[str, Any]:
+        async with self._private_lock:
+            result = await self._private_post_with_retry(endpoint, data=data)
+            await asyncio.sleep(self._settings.kraken_private_rate_limit_seconds)
+            return _result_dict(result.payload)
+
+    async def balances(self) -> dict[str, Any]:
+        return await self._throttled_private_call("/0/private/Balance")
+
+    async def place_market_order(
+        self,
+        *,
+        pair: str,
+        side: str,
+        volume: float,
+        user_ref: int | None = None,
+    ) -> dict[str, Any]:
+        normalized_side = side.lower()
+        if normalized_side not in {"buy", "sell"}:
+            raise ValueError("side must be 'buy' or 'sell'")
+        if volume <= 0.0:
+            raise ValueError("volume must be > 0.0")
+        if user_ref is not None and user_ref < 0:
+            raise ValueError("user_ref must be >= 0")
+
+        data = {
+            "pair": pair,
+            "type": normalized_side,
+            "ordertype": "market",
+            "volume": str(volume),
+        }
+        if user_ref is not None:
+            data["userref"] = str(user_ref)
+
+        return await self._throttled_private_call(
+            "/0/private/AddOrder",
+            data=data,
+        )
+
+    async def place_limit_order(
+        self,
+        *,
+        pair: str,
+        side: str,
+        volume: float,
+        price: float,
+        user_ref: int | None = None,
+    ) -> dict[str, Any]:
+        normalized_side = side.lower()
+        if normalized_side not in {"buy", "sell"}:
+            raise ValueError("side must be 'buy' or 'sell'")
+        if volume <= 0.0:
+            raise ValueError("volume must be > 0.0")
+        if price <= 0.0:
+            raise ValueError("price must be > 0.0")
+        if user_ref is not None and user_ref < 0:
+            raise ValueError("user_ref must be >= 0")
+
+        data = {
+            "pair": pair,
+            "type": normalized_side,
+            "ordertype": "limit",
+            "price": str(price),
+            "volume": str(volume),
+        }
+        if user_ref is not None:
+            data["userref"] = str(user_ref)
+
+        return await self._throttled_private_call(
+            "/0/private/AddOrder",
+            data=data,
+        )
+
+    async def query_order(
+        self,
+        *,
+        order_id: str,
+        include_trades: bool = True,
+    ) -> dict[str, Any]:
+        if not order_id.strip():
+            raise ValueError("order_id must be non-empty")
+
+        return await self._throttled_private_call(
+            "/0/private/QueryOrders",
+            data={
+                "txid": order_id,
+                "trades": "true" if include_trades else "false",
+            },
+        )
+
+    async def cancel_order(self, *, order_id: str) -> dict[str, Any]:
+        if not order_id.strip():
+            raise ValueError("order_id must be non-empty")
+
+        return await self._throttled_private_call(
+            "/0/private/CancelOrder",
+            data={"txid": order_id},
+        )

src/arbitrade/exchange/kraken_ws.py

@@ -0,0 +1,177 @@
+from __future__ import annotations
+
+import asyncio
+import time
+from collections.abc import AsyncIterator
+from dataclasses import dataclass
+from datetime import UTC, datetime
+from typing import Any
+
+import orjson
+import structlog
+import websockets
+
+from arbitrade.alerting.notifier import AlertSeverity, SupportsAlerts
+from arbitrade.config.settings import Settings
+from arbitrade.exchange.models import BookDelta, BookLevel
+
+_LOG = structlog.get_logger(__name__)
+
+
+@dataclass(slots=True)
+class WsMessage:
+    received_at: datetime
+    payload: dict[str, Any]
+
+
+class KrakenWsClient:
+    def __init__(self, settings: Settings, *, alert_notifier: SupportsAlerts | None = None) -> None:
+        self._settings = settings
+        self._last_message_at: datetime | None = None
+        self._stop = asyncio.Event()
+        self._alert_notifier = alert_notifier
+        self._has_connected_once = False
+        self._was_disconnected = False
+
+    @property
+    def is_stale(self) -> bool:
+        if self._last_message_at is None:
+            return True
+        return (
+            datetime.now(UTC) - self._last_message_at
+        ).total_seconds() > self._settings.ws_max_staleness_seconds
+
+    async def stop(self) -> None:
+        self._stop.set()
+
+    async def connect_stream(self) -> AsyncIterator[WsMessage]:
+        delay = 1.0
+        while not self._stop.is_set():
+            try:
+                async with websockets.connect(
+                    self._settings.kraken_ws_url, max_size=2_000_000
+                ) as ws:
+                    _LOG.info("kraken_ws_connected", url=self._settings.kraken_ws_url)
+                    if self._has_connected_once and self._was_disconnected:
+                        await self._notify(
+                            category="system",
+                            severity="info",
+                            title="WebSocket reconnected",
+                            message="Kraken WebSocket connection restored.",
+                            details={"url": self._settings.kraken_ws_url},
+                        )
+                    self._has_connected_once = True
+                    self._was_disconnected = False
+                    delay = 1.0
+                    async for raw in self._recv_loop(ws):
+                        yield raw
+            except Exception as exc:
+                _LOG.warning("kraken_ws_disconnected", error=str(exc), reconnect_in=delay)
+                self._was_disconnected = True
+                await self._notify(
+                    category="system",
+                    severity="warning",
+                    title="WebSocket disconnected",
+                    message="Kraken WebSocket disconnected, reconnect scheduled.",
+                    details={
+                        "error": str(exc),
+                        "reconnect_in_seconds": f"{delay}",
+                    },
+                )
+                await asyncio.sleep(delay)
+                delay = min(delay * 2, 30.0)
+
+    async def _recv_loop(self, ws: Any) -> AsyncIterator[WsMessage]:
+        while not self._stop.is_set():
+            t0 = time.perf_counter()
+            try:
+                raw = await asyncio.wait_for(
+                    ws.recv(), timeout=self._settings.ws_heartbeat_timeout_seconds
+                )
+            except TimeoutError:
+                await self._notify(
+                    category="system",
+                    severity="critical",
+                    title="WebSocket staleness abort",
+                    message="No WebSocket heartbeat within configured timeout; reconnecting.",
+                    details={
+                        "heartbeat_timeout_seconds": (
+                            f"{self._settings.ws_heartbeat_timeout_seconds}"
+                        ),
+                    },
+                )
+                raise
+            parse_start = time.perf_counter()
+            payload = orjson.loads(raw)
+            self._last_message_at = datetime.now(UTC)
+
+            _LOG.debug(
+                "kraken_ws_message",
+                recv_latency_ms=(parse_start - t0) * 1000,
+                parse_latency_ms=(time.perf_counter() - parse_start) * 1000,
+            )
+            if isinstance(payload, dict):
+                yield WsMessage(received_at=self._last_message_at, payload=payload)
+
+    async def _notify(
+        self,
+        *,
+        category: str,
+        severity: AlertSeverity,
+        title: str,
+        message: str,
+        details: dict[str, str] | None = None,
+    ) -> None:
+        if self._alert_notifier is None:
+            return
+        await self._alert_notifier.notify(
+            category=category,
+            severity=severity,
+            title=title,
+            message=message,
+            details=details,
+        )
+
+    @staticmethod
+    def parse_book_delta(message: dict[str, Any]) -> BookDelta | None:
+        # Kraken v2 book update shape can vary by channel; keep parser defensive.
+        channel = str(message.get("channel", ""))
+        if "book" not in channel:
+            return None
+
+        symbol = str(message.get("symbol", ""))
+        data = message.get("data")
+        if not isinstance(data, list) or not data:
+            return None
+
+        first = data[0]
+        if not isinstance(first, dict):
+            return None
+
+        bids = [
+            BookLevel(price=float(level["price"]), volume=float(level["qty"]))
+            for level in first.get("bids", [])
+            if isinstance(level, dict) and "price" in level and "qty" in level
+        ]
+        asks = [
+            BookLevel(price=float(level["price"]), volume=float(level["qty"]))
+            for level in first.get("asks", [])
+            if isinstance(level, dict) and "price" in level and "qty" in level
+        ]
+
+        checksum: int | None = None
+        raw_checksum = first.get("checksum")
+        if isinstance(raw_checksum, int):
+            checksum = raw_checksum
+
+        source_timestamp_ms: int | None = None
+        if isinstance(first.get("timestamp"), int):
+            source_timestamp_ms = first["timestamp"]
+
+        return BookDelta(
+            symbol=symbol,
+            bids=bids,
+            asks=asks,
+            checksum=checksum,
+            source_timestamp_ms=source_timestamp_ms,
+        )

src/arbitrade/exchange/models.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import UTC, datetime
+from typing import Any
+
+
+@dataclass(slots=True)
+class KrakenApiResult:
+    endpoint: str
+    payload: dict[str, Any]
+
+
+@dataclass(slots=True)
+class LatencySample:
+    stage: str
+    at: datetime
+    latency_ms: float
+
+    @classmethod
+    def now(cls, stage: str, latency_ms: float) -> LatencySample:
+        return cls(stage=stage, at=datetime.now(UTC), latency_ms=latency_ms)
+
+
+@dataclass(slots=True)
+class BookLevel:
+    price: float
+    volume: float
+
+
+@dataclass(slots=True)
+class BookDelta:
+    symbol: str
+    bids: list[BookLevel]
+    asks: list[BookLevel]
+    checksum: int | None = None
+    source_timestamp_ms: int | None = None

src/arbitrade/exchange/signing.py

@@ -0,0 +1,14 @@
+from __future__ import annotations
+
+import base64
+import hashlib
+import hmac
+from functools import lru_cache
+
+
+@lru_cache(maxsize=2048)
+def sign_kraken_private_path(path: str, nonce: str, post_data: str, api_secret: str) -> str:
+    message = nonce.encode("utf-8") + post_data.encode("utf-8")
+    sha256 = hashlib.sha256(message).digest()
+    mac = hmac.new(base64.b64decode(api_secret), path.encode("utf-8") + sha256, hashlib.sha512)
+    return base64.b64encode(mac.digest()).decode("utf-8")

src/arbitrade/execution/__init__.py

@@ -0,0 +1,32 @@
+"""Trade execution helpers."""
+
+from arbitrade.execution.fill_monitor import (
+    FillMonitor,
+    FillMonitorResult,
+    OrderFillState,
+)
+from arbitrade.execution.idempotency import (
+    IdempotencyKeyFactory,
+    OrderReconciler,
+    ReconciliationReport,
+)
+from arbitrade.execution.recovery import PartialFillRecovery, RecoveryAction
+from arbitrade.execution.sequencer import (
+    ExecutionLeg,
+    TriangularExecutionResult,
+    TriangularExecutionSequencer,
+)
+
+__all__ = [
+    "ExecutionLeg",
+    "OrderFillState",
+    "FillMonitorResult",
+    "FillMonitor",
+    "IdempotencyKeyFactory",
+    "ReconciliationReport",
+    "OrderReconciler",
+    "RecoveryAction",
+    "PartialFillRecovery",
+    "TriangularExecutionResult",
+    "TriangularExecutionSequencer",
+]

src/arbitrade/execution/fill_monitor.py

@@ -0,0 +1,133 @@
+from __future__ import annotations
+
+import asyncio
+import time
+from collections.abc import Callable
+from dataclasses import dataclass
+from datetime import UTC, datetime
+from typing import Any, Protocol
+
+
+class SupportsOrderStatusPolling(Protocol):
+    async def query_order(
+        self, *, order_id: str, include_trades: bool = True
+    ) -> dict[str, Any]: ...
+
+
+@dataclass(frozen=True, slots=True)
+class OrderFillState:
+    order_id: str
+    status: str
+    filled_volume: float | None
+    avg_price: float | None
+    updated_at: datetime
+    source: str
+
+    @property
+    def is_terminal(self) -> bool:
+        return self.status in {"closed", "canceled", "expired"}
+
+
+@dataclass(frozen=True, slots=True)
+class FillMonitorResult:
+    order_id: str
+    timed_out: bool
+    terminal_state: OrderFillState | None
+    last_state: OrderFillState | None
+    elapsed_seconds: float
+
+
+class FillMonitor:
+    def __init__(
+        self,
+        poll_client: SupportsOrderStatusPolling,
+        *,
+        poll_interval_seconds: float = 0.5,
+        max_wait_seconds: float = 10.0,
+        ws_status_provider: Callable[[str], OrderFillState | None] | None = None,
+    ) -> None:
+        if poll_interval_seconds <= 0.0:
+            raise ValueError("poll_interval_seconds must be > 0.0")
+        if max_wait_seconds <= 0.0:
+            raise ValueError("max_wait_seconds must be > 0.0")
+
+        self._poll_client = poll_client
+        self._poll_interval_seconds = poll_interval_seconds
+        self._max_wait_seconds = max_wait_seconds
+        self._ws_status_provider = ws_status_provider
+
+    @staticmethod
+    def _to_float(value: Any) -> float | None:
+        if value is None:
+            return None
+        try:
+            return float(value)
+        except (TypeError, ValueError):
+            return None
+
+    @classmethod
+    def _state_from_payload(
+        cls, order_id: str, payload: dict[str, Any], *, source: str
+    ) -> OrderFillState:
+        status = str(payload.get("status", "unknown")).lower()
+        return OrderFillState(
+            order_id=order_id,
+            status=status,
+            filled_volume=cls._to_float(payload.get("vol_exec")),
+            avg_price=cls._to_float(payload.get("price") or payload.get("avg_price")),
+            updated_at=datetime.now(UTC),
+            source=source,
+        )
+
+    @classmethod
+    def _extract_order_payload(cls, order_id: str, response: dict[str, Any]) -> dict[str, Any]:
+        if order_id in response and isinstance(response[order_id], dict):
+            payload = response[order_id]
+            return {str(key): value for key, value in payload.items()}
+        return response
+
+    async def wait_for_terminal_fill(self, order_id: str) -> FillMonitorResult:
+        if not order_id.strip():
+            raise ValueError("order_id must be non-empty")
+
+        started = time.monotonic()
+        last_state: OrderFillState | None = None
+
+        while True:
+            elapsed = time.monotonic() - started
+            if elapsed >= self._max_wait_seconds:
+                return FillMonitorResult(
+                    order_id=order_id,
+                    timed_out=True,
+                    terminal_state=None,
+                    last_state=last_state,
+                    elapsed_seconds=elapsed,
+                )
+
+            if self._ws_status_provider is not None:
+                ws_state = self._ws_status_provider(order_id)
+                if ws_state is not None:
+                    last_state = ws_state
+                    if ws_state.is_terminal:
+                        return FillMonitorResult(
+                            order_id=order_id,
+                            timed_out=False,
+                            terminal_state=ws_state,
+                            last_state=ws_state,
+                            elapsed_seconds=elapsed,
+                        )
+
+            response = await self._poll_client.query_order(order_id=order_id, include_trades=True)
+            payload = self._extract_order_payload(order_id, response)
+            polled_state = self._state_from_payload(order_id, payload, source="rest_poll")
+            last_state = polled_state
+            if polled_state.is_terminal:
+                return FillMonitorResult(
+                    order_id=order_id,
+                    timed_out=False,
+                    terminal_state=polled_state,
+                    last_state=polled_state,
+                    elapsed_seconds=time.monotonic() - started,
+                )
+
+            await asyncio.sleep(self._poll_interval_seconds)

src/arbitrade/execution/idempotency.py

@@ -0,0 +1,105 @@
+from __future__ import annotations
+
+import hashlib
+from dataclasses import dataclass
+from typing import Any, Protocol
+
+from arbitrade.detection.engine import OpportunityEvent
+from arbitrade.execution.sequencer import ExecutionLeg
+
+
+class SupportsOrderHistoryLookup(Protocol):
+    async def query_order(
+        self, *, order_id: str, include_trades: bool = True
+    ) -> dict[str, Any]: ...
+
+
+@dataclass(frozen=True, slots=True)
+class ReconciliationReport:
+    order_id: str
+    user_ref: int
+    status: str
+    filled_volume: float | None
+    avg_price: float | None
+    is_terminal: bool
+    matches_request: bool
+    raw_payload: dict[str, Any]
+
+
+class IdempotencyKeyFactory:
+    def user_ref_for_leg(self, event: OpportunityEvent, leg: ExecutionLeg, leg_index: int) -> int:
+        material = "|".join(
+            [
+                event.cycle,
+                event.updated_pair,
+                leg.from_currency,
+                leg.to_currency,
+                leg.pair,
+                leg.side,
+                f"{leg.volume:.12f}",
+                str(leg_index),
+            ]
+        ).encode("utf-8")
+        digest = hashlib.sha256(material).digest()
+        value = int.from_bytes(digest[:8], "big") % 2_147_483_647
+        return value or 1
+
+
+class OrderReconciler:
+    def __init__(self, history_client: SupportsOrderHistoryLookup) -> None:
+        self._history_client = history_client
+
+    @staticmethod
+    def _to_float(value: Any) -> float | None:
+        if value is None:
+            return None
+        try:
+            return float(value)
+        except (TypeError, ValueError):
+            return None
+
+    @staticmethod
+    def _extract_payload(order_id: str, response: dict[str, Any]) -> dict[str, Any]:
+        if order_id in response and isinstance(response[order_id], dict):
+            payload = response[order_id]
+            return {str(key): value for key, value in payload.items()}
+        return response
+
+    async def reconcile_order(
+        self,
+        *,
+        order_id: str,
+        user_ref: int,
+        expected_pair: str,
+        expected_side: str,
+        expected_volume: float,
+    ) -> ReconciliationReport:
+        if not order_id.strip():
+            raise ValueError("order_id must be non-empty")
+
+        response = await self._history_client.query_order(order_id=order_id, include_trades=True)
+        payload = self._extract_payload(order_id, response)
+        status = str(payload.get("status", "unknown")).lower()
+        filled_volume = self._to_float(payload.get("vol_exec"))
+        avg_price = self._to_float(payload.get("price") or payload.get("avg_price"))
+        reported_pair = str(payload.get("pair", expected_pair))
+        reported_side = str(payload.get("type", expected_side)).lower()
+        matches_request = (
+            reported_pair == expected_pair
+            and reported_side == expected_side.lower()
+            and (
+                expected_volume <= 0.0 or filled_volume is None or filled_volume <= expected_volume
+            )
+            and payload.get("userref") in {None, str(user_ref), user_ref}
+        )
+
+        return ReconciliationReport(
+            order_id=order_id,
+            user_ref=user_ref,
+            status=status,
+            filled_volume=filled_volume,
+            avg_price=avg_price,
+            is_terminal=status in {"closed", "canceled", "expired"},
+            matches_request=matches_request,
+            raw_payload=payload,
+        )

src/arbitrade/execution/recovery.py

@@ -0,0 +1,98 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Any, Protocol
+
+from arbitrade.execution.fill_monitor import FillMonitorResult, OrderFillState
+
+
+class SupportsOrderLifecycle(Protocol):
+    async def cancel_order(self, *, order_id: str) -> dict[str, Any]: ...
+
+    async def place_market_order(
+        self, *, pair: str, side: str, volume: float
+    ) -> dict[str, Any]: ...
+
+
+@dataclass(frozen=True, slots=True)
+class RecoveryAction:
+    order_id: str
+    canceled: bool
+    hedged: bool
+    hedge_pair: str | None = None
+    hedge_side: str | None = None
+    hedge_volume: float | None = None
+    cancel_response: dict[str, Any] | None = None
+    hedge_response: dict[str, Any] | None = None
+    reason: str | None = None
+
+
+class PartialFillRecovery:
+    def __init__(self, rest_client: SupportsOrderLifecycle) -> None:
+        self._rest_client = rest_client
+
+    @staticmethod
+    def _counter_side(side: str) -> str:
+        normalized = side.lower()
+        if normalized == "buy":
+            return "sell"
+        if normalized == "sell":
+            return "buy"
+        raise ValueError("side must be 'buy' or 'sell'")
+
+    @staticmethod
+    def _residual_volume(terminal_state: OrderFillState | None, requested_volume: float) -> float:
+        if requested_volume <= 0.0:
+            raise ValueError("requested_volume must be > 0.0")
+        if terminal_state is None or terminal_state.filled_volume is None:
+            return requested_volume
+        residual = requested_volume - terminal_state.filled_volume
+        return residual if residual > 0.0 else 0.0
+
+    async def recover_partial_fill(
+        self,
+        *,
+        order_id: str,
+        pair: str,
+        side: str,
+        requested_volume: float,
+        fill_result: FillMonitorResult,
+    ) -> RecoveryAction:
+        if not order_id.strip():
+            raise ValueError("order_id must be non-empty")
+
+        cancel_response: dict[str, Any] | None = None
+        hedge_response: dict[str, Any] | None = None
+        hedged = False
+        canceled = False
+        reason = None
+
+        state = fill_result.terminal_state or fill_result.last_state
+        residual_volume = self._residual_volume(state, requested_volume)
+
+        if state is not None and state.status in {"open", "partial"}:
+            cancel_response = await self._rest_client.cancel_order(order_id=order_id)
+            canceled = True
+            reason = f"canceled_{state.status}_order"
+
+        if residual_volume > 0.0 and fill_result.timed_out:
+            hedge_response = await self._rest_client.place_market_order(
+                pair=pair,
+                side=self._counter_side(side),
+                volume=residual_volume,
+            )
+            hedged = True
+            if reason is None:
+                reason = "hedged_timed_out_order"
+
+        return RecoveryAction(
+            order_id=order_id,
+            canceled=canceled,
+            hedged=hedged,
+            hedge_pair=pair if hedged else None,
+            hedge_side=self._counter_side(side) if hedged else None,
+            hedge_volume=residual_volume if hedged else None,
+            cancel_response=cancel_response,
+            hedge_response=hedge_response,
+            reason=reason,
+        )

src/arbitrade/execution/sequencer.py

@@ -0,0 +1,288 @@
+from __future__ import annotations
+
+from collections.abc import Callable, Sequence
+from dataclasses import dataclass
+from datetime import UTC, datetime
+from typing import Any, Protocol
+
+from arbitrade.alerting.notifier import SupportsAlerts
+from arbitrade.detection.engine import OpportunityEvent
+from arbitrade.storage.executions import AsyncExecutionWriter
+from arbitrade.storage.repositories import (
+    AuditRecord,
+    AuditRepository,
+    OrderRecord,
+    PnLRecord,
+    TradeRecord,
+)
+
+
+class SupportsOrderPlacement(Protocol):
+    async def place_market_order(
+        self, *, pair: str, side: str, volume: float
+    ) -> dict[str, Any]: ...
+
+
+@dataclass(frozen=True, slots=True)
+class ExecutionLeg:
+    from_currency: str
+    to_currency: str
+    pair: str
+    side: str
+    volume: float
+
+
+@dataclass(frozen=True, slots=True)
+class TriangularExecutionResult:
+    success: bool
+    requested_legs: tuple[ExecutionLeg, ...]
+    completed_legs: int
+    responses: tuple[dict[str, Any], ...]
+    failure_reason: str | None = None
+
+
+class TriangularExecutionSequencer:
+    def __init__(
+        self,
+        rest_client: SupportsOrderPlacement,
+        *,
+        available_pairs: Sequence[str],
+        volume_for_leg: Callable[[OpportunityEvent, ExecutionLeg, int], float] | None = None,
+        execution_writer: AsyncExecutionWriter | None = None,
+        alert_notifier: SupportsAlerts | None = None,
+        audit_repository: AuditRepository | None = None,
+    ) -> None:
+        self._rest_client = rest_client
+        self._available_pairs = {self._normalize_pair(pair) for pair in available_pairs}
+        self._volume_for_leg = volume_for_leg or self._default_volume_for_leg
+        self._execution_writer = execution_writer
+        self._alert_notifier = alert_notifier
+        self._audit_repository = audit_repository
+
+    @staticmethod
+    def _normalize_pair(pair: str) -> str:
+        normalized = pair.strip().upper().replace("-", "/")
+        if "/" not in normalized:
+            return normalized
+        base, quote = normalized.split("/", 1)
+        return f"{base}/{quote}"
+
+    @staticmethod
+    def _default_volume_for_leg(event: OpportunityEvent, _leg: ExecutionLeg, _idx: int) -> float:
+        if event.allocated_capital <= 0.0:
+            raise ValueError("allocated_capital must be > 0.0")
+        return event.allocated_capital
+
+    def _resolve_leg(self, from_currency: str, to_currency: str, volume: float) -> ExecutionLeg:
+        from_cur = from_currency.upper()
+        to_cur = to_currency.upper()
+
+        buy_pair = f"{to_cur}/{from_cur}"
+        if buy_pair in self._available_pairs:
+            return ExecutionLeg(
+                from_currency=from_cur,
+                to_currency=to_cur,
+                pair=buy_pair,
+                side="buy",
+                volume=volume,
+            )
+
+        sell_pair = f"{from_cur}/{to_cur}"
+        if sell_pair in self._available_pairs:
+            return ExecutionLeg(
+                from_currency=from_cur,
+                to_currency=to_cur,
+                pair=sell_pair,
+                side="sell",
+                volume=volume,
+            )
+
+        raise ValueError(f"No tradable pair for leg {from_cur}->{to_cur}")
+
+    def _build_legs(self, event: OpportunityEvent) -> tuple[ExecutionLeg, ...]:
+        currencies = [part.strip().upper() for part in event.cycle.split("->") if part.strip()]
+        if len(currencies) < 4 or currencies[0] != currencies[-1]:
+            raise ValueError("cycle must be a closed triangular path like A->B->C->A")
+
+        if len(currencies) != 4:
+            raise ValueError("cycle must contain exactly three unique currencies")
+
+        legs: list[ExecutionLeg] = []
+        for idx in range(3):
+            from_currency = currencies[idx]
+            to_currency = currencies[idx + 1]
+            placeholder_leg = ExecutionLeg(
+                from_currency=from_currency,
+                to_currency=to_currency,
+                pair="",
+                side="buy",
+                volume=0.0,
+            )
+            volume = self._volume_for_leg(event, placeholder_leg, idx)
+            if volume <= 0.0:
+                raise ValueError("volume_for_leg must return a positive volume")
+            legs.append(self._resolve_leg(from_currency, to_currency, volume))
+
+        return tuple(legs)
+
+    @staticmethod
+    def _trade_ref_for_event(event: OpportunityEvent) -> str:
+        material = (
+            f"{event.cycle}|{event.updated_pair}|"
+            f"{event.detected_at.timestamp():.6f}|"
+            f"{event.allocated_capital:.12f}"
+        )
+        return material.encode("utf-8").hex()[:32]
+
+    @staticmethod
+    def _order_ref_from_response(response: dict[str, Any], default: str) -> str:
+        txid = response.get("txid")
+        if isinstance(txid, list) and txid:
+            return str(txid[0])
+        if isinstance(txid, str) and txid.strip():
+            return txid
+        return default
+
+    async def execute(self, event: OpportunityEvent) -> TriangularExecutionResult:
+        legs = self._build_legs(event)
+        responses: list[dict[str, Any]] = []
+        trade_ref = self._trade_ref_for_event(event)
+        started_at = datetime.now(UTC)
+
+        for idx, leg in enumerate(legs):
+            try:
+                response = await self._rest_client.place_market_order(
+                    pair=leg.pair,
+                    side=leg.side,
+                    volume=leg.volume,
+                )
+            except Exception as exc:
+                if self._audit_repository is not None:
+                    self._audit_repository.insert(
+                        AuditRecord(
+                            occurred_at=datetime.now(UTC),
+                            actor="execution_engine",
+                            event_type="execution.trade.failed",
+                            decision="rejected",
+                            payload={
+                                "cycle": event.cycle,
+                                "failed_leg_index": idx,
+                                "error": str(exc),
+                            },
+                            correlation_id=trade_ref,
+                        )
+                    )
+                if self._alert_notifier is not None:
+                    await self._alert_notifier.notify(
+                        category="error",
+                        severity="error",
+                        title="Trade execution failed",
+                        message="Triangular execution failed before completing all legs.",
+                        details={
+                            "cycle": event.cycle,
+                            "failed_leg_index": str(idx),
+                            "error": str(exc),
+                        },
+                    )
+                if self._execution_writer is not None:
+                    await self._execution_writer.enqueue(
+                        TradeRecord(
+                            trade_ref=trade_ref,
+                            started_at=started_at,
+                            finished_at=datetime.now(UTC),
+                            status="failed",
+                            realized_pnl=None,
+                            estimated_pnl=event.est_profit,
+                            capital_used=event.allocated_capital,
+                            cycle=event.cycle,
+                            leg_count=len(legs),
+                        )
+                    )
+                return TriangularExecutionResult(
+                    success=False,
+                    requested_legs=legs,
+                    completed_legs=idx,
+                    responses=tuple(responses),
+                    failure_reason=str(exc),
+                )
+
+            responses.append(response)
+
+            if self._execution_writer is not None:
+                order_ref = self._order_ref_from_response(response, f"leg-{idx}")
+                await self._execution_writer.enqueue(
+                    OrderRecord(
+                        trade_ref=trade_ref,
+                        order_ref=order_ref,
+                        leg_index=idx,
+                        pair=leg.pair,
+                        side=leg.side,
+                        volume=leg.volume,
+                        user_ref=None,
+                        status=str(response.get("status", "submitted")),
+                        filled_volume=None,
+                        avg_price=None,
+                        raw_response=response,
+                        recorded_at=datetime.now(UTC),
+                    )
+                )
+
+        if self._execution_writer is not None:
+            await self._execution_writer.enqueue(
+                TradeRecord(
+                    trade_ref=trade_ref,
+                    started_at=started_at,
+                    finished_at=datetime.now(UTC),
+                    status="filled",
+                    realized_pnl=None,
+                    estimated_pnl=event.est_profit,
+                    capital_used=event.allocated_capital,
+                    cycle=event.cycle,
+                    leg_count=len(legs),
+                )
+            )
+            await self._execution_writer.enqueue(
+                PnLRecord(
+                    trade_ref=trade_ref,
+                    recorded_at=datetime.now(UTC),
+                    kind="estimated",
+                    pnl_usd=event.est_profit,
+                    source="triangular_sequencer",
+                )
+            )
+
+        if self._alert_notifier is not None:
+            await self._alert_notifier.notify(
+                category="trade",
+                severity="warning" if event.est_profit < 0.0 else "info",
+                title="Trade execution completed",
+                message="Triangular execution completed all requested legs.",
+                details={
+                    "cycle": event.cycle,
+                    "completed_legs": str(len(legs)),
+                    "estimated_pnl_usd": f"{event.est_profit}",
+                },
+            )
+
+        if self._audit_repository is not None:
+            self._audit_repository.insert(
+                AuditRecord(
+                    occurred_at=datetime.now(UTC),
+                    actor="execution_engine",
+                    event_type="execution.trade.completed",
+                    decision="approved",
+                    payload={
+                        "cycle": event.cycle,
+                        "completed_legs": len(legs),
+                        "estimated_pnl_usd": event.est_profit,
+                    },
+                    correlation_id=trade_ref,
+                )
+            )
+
+        return TriangularExecutionResult(
+            success=True,
+            requested_legs=legs,
+            completed_legs=len(legs),
+            responses=tuple(responses),
+        )

src/arbitrade/market_data/__init__.py

@@ -0,0 +1 @@
+"""Market data ingestion and book cache package."""

src/arbitrade/market_data/feed.py

@@ -0,0 +1,485 @@
+from __future__ import annotations
+
+import time
+from collections.abc import Awaitable, Callable, Mapping
+from dataclasses import dataclass
+from datetime import UTC, datetime
+
+import structlog
+
+from arbitrade.alerting.notifier import SupportsAlerts, dispatch_alert_nowait
+from arbitrade.detection.engine import IncrementalCycleDetector, OpportunityEvent
+from arbitrade.exchange.kraken_ws import KrakenWsClient
+from arbitrade.market_data.order_book import OrderBook
+from arbitrade.risk.kill_switch import KillSwitch
+from arbitrade.risk.loss_limits import LossLimitGuard
+from arbitrade.risk.pre_trade import PreTradeValidator
+from arbitrade.risk.stop_conditions import StopConditionsGuard
+from arbitrade.risk.trade_limits import TradeLimitsGuard
+from arbitrade.storage.market_snapshots import AsyncMarketSnapshotWriter, MarketSnapshot
+from arbitrade.storage.opportunities import AsyncOpportunityWriter
+from arbitrade.storage.repositories import AuditRecord, AuditRepository
+
+_LOG = structlog.get_logger(__name__)
+
+
+@dataclass(frozen=True, slots=True)
+class ExecutionOutcome:
+    realized_pnl: float | None = None
+    close_trade: bool = True
+
+
+class MarketDataFeed:
+    def __init__(
+        self,
+        ws_client: KrakenWsClient,
+        snapshot_writer: AsyncMarketSnapshotWriter,
+        detector: IncrementalCycleDetector | None = None,
+        opportunity_writer: AsyncOpportunityWriter | None = None,
+        paper_trading_mode: bool = True,
+        opportunity_executor: (
+            Callable[[OpportunityEvent], Awaitable[ExecutionOutcome | float | None]] | None
+        ) = None,
+        trade_capital: float = 1.0,
+        max_trade_capital: float | None = None,
+        loss_limit_guard: LossLimitGuard | None = None,
+        trade_limits_guard: TradeLimitsGuard | None = None,
+        pre_trade_validator: PreTradeValidator | None = None,
+        balance_provider: Callable[[], Mapping[str, float]] | None = None,
+        quote_balance_asset: str = "USD",
+        kill_switch: KillSwitch | None = None,
+        stop_conditions_guard: StopConditionsGuard | None = None,
+        alert_notifier: SupportsAlerts | None = None,
+        audit_repository: AuditRepository | None = None,
+    ) -> None:
+        self._ws_client = ws_client
+        self._snapshot_writer = snapshot_writer
+        self._books: dict[str, OrderBook] = {}
+        self._detector = detector
+        self._opportunity_writer = opportunity_writer
+        self._paper_trading_mode = paper_trading_mode
+        self._opportunity_executor = opportunity_executor
+        self._trade_capital = trade_capital
+        self._max_trade_capital = max_trade_capital
+        self._loss_limit_guard = loss_limit_guard
+        self._trade_limits_guard = trade_limits_guard
+        self._pre_trade_validator = pre_trade_validator
+        self._balance_provider = balance_provider
+        self._quote_balance_asset = quote_balance_asset.upper()
+        self._kill_switch = kill_switch
+        self._stop_conditions_guard = stop_conditions_guard
+        self._alert_notifier = alert_notifier
+        self._audit_repository = audit_repository
+
+        if self._trade_capital <= 0.0:
+            raise ValueError("trade_capital must be > 0.0")
+        if self._max_trade_capital is not None and self._max_trade_capital <= 0.0:
+            raise ValueError("max_trade_capital must be > 0.0")
+
+    @property
+    def books(self) -> dict[str, OrderBook]:
+        return self._books
+
+    def _effective_trade_capital(self) -> float:
+        if self._max_trade_capital is None:
+            return self._trade_capital
+        return min(self._trade_capital, self._max_trade_capital)
+
+    @staticmethod
+    def _exposure_for_event(event: OpportunityEvent) -> dict[str, float]:
+        currencies = [part for part in event.cycle.split("->") if part]
+        if len(currencies) < 2:
+            return {}
+
+        start = currencies[0]
+        exposure_assets = {currency for currency in currencies[1:] if currency != start}
+        return {asset: event.allocated_capital for asset in exposure_assets}
+
+    async def run(self) -> None:
+        async for message in self._ws_client.connect_stream():
+            parse_start = time.perf_counter()
+            delta = self._ws_client.parse_book_delta(message.payload)
+            if delta is None:
+                continue
+
+            book = self._books.setdefault(delta.symbol, OrderBook())
+            book.apply_bids(delta.bids)
+            book.apply_asks(delta.asks)
+
+            checksum_ok = True
+            if delta.checksum is not None:
+                checksum_ok = book.compute_checksum() == delta.checksum
+
+            apply_latency_ms = (time.perf_counter() - parse_start) * 1000
+            source_latency_ms: float | None = None
+            if delta.source_timestamp_ms is not None:
+                source_latency_ms = datetime.now(UTC).timestamp() * 1000 - float(
+                    delta.source_timestamp_ms
+                )
+
+            _LOG.info(
+                "book_delta_applied",
+                symbol=delta.symbol,
+                bids=len(delta.bids),
+                asks=len(delta.asks),
+                checksum_ok=checksum_ok,
+                apply_latency_ms=apply_latency_ms,
+                source_latency_ms=source_latency_ms,
+            )
+
+            if self._stop_conditions_guard is not None:
+                self._stop_conditions_guard.observe_latency(
+                    source_latency_ms=source_latency_ms,
+                    apply_latency_ms=apply_latency_ms,
+                )
+                if self._stop_conditions_guard.is_halted:
+                    if self._kill_switch is not None and not self._kill_switch.is_active:
+                        self._kill_switch.activate(
+                            reason=self._stop_conditions_guard.halted_reason
+                            or "stop_conditions_halted",
+                        )
+                    _LOG.warning(
+                        "stop_condition_halt_triggered",
+                        reason=self._stop_conditions_guard.halted_reason,
+                        symbol=delta.symbol,
+                    )
+                    if self._audit_repository is not None:
+                        self._audit_repository.insert(
+                            AuditRecord(
+                                occurred_at=datetime.now(UTC),
+                                actor="risk_manager",
+                                event_type="risk.stop_condition_halt",
+                                decision="rejected",
+                                payload={
+                                    "reason": self._stop_conditions_guard.halted_reason
+                                    or "unknown",
+                                    "symbol": delta.symbol,
+                                },
+                            )
+                        )
+
+            if self._detector is not None:
+                opportunities = self._detector.opportunities_for_updated_pair(
+                    delta.symbol,
+                    self._books,
+                    base_capital=self._effective_trade_capital(),
+                )
+                _LOG.debug(
+                    "incremental_opportunity_scores",
+                    symbol=delta.symbol,
+                    opportunities=len(opportunities),
+                )
+
+                for event in opportunities:
+                    if self._audit_repository is not None:
+                        self._audit_repository.insert(
+                            AuditRecord(
+                                occurred_at=datetime.now(UTC),
+                                actor="detector",
+                                event_type="detector.opportunity",
+                                decision="scored",
+                                payload={
+                                    "cycle": event.cycle,
+                                    "updated_pair": event.updated_pair,
+                                    "net_pct": event.net_pct,
+                                    "est_profit": event.est_profit,
+                                },
+                            )
+                        )
+                    _LOG.info(
+                        "opportunity_detected",
+                        cycle=event.cycle,
+                        updated_pair=event.updated_pair,
+                        gross_pct=event.gross_pct,
+                        net_pct=event.net_pct,
+                        est_profit=event.est_profit,
+                        mode="paper" if self._paper_trading_mode else "live",
+                    )
+
+                    if self._opportunity_writer is not None:
+                        await self._opportunity_writer.enqueue(event)
+
+                    if self._paper_trading_mode:
+                        _LOG.info(
+                            "paper_trade_simulated",
+                            cycle=event.cycle,
+                            updated_pair=event.updated_pair,
+                            net_pct=event.net_pct,
+                        )
+                        if self._audit_repository is not None:
+                            self._audit_repository.insert(
+                                AuditRecord(
+                                    occurred_at=datetime.now(UTC),
+                                    actor="execution_engine",
+                                    event_type="execution.paper_trade",
+                                    decision="skipped",
+                                    payload={
+                                        "cycle": event.cycle,
+                                        "updated_pair": event.updated_pair,
+                                    },
+                                )
+                            )
+                        continue
+
+                    if self._opportunity_executor is None:
+                        _LOG.warning(
+                            "live_trade_skipped_no_executor",
+                            cycle=event.cycle,
+                            updated_pair=event.updated_pair,
+                        )
+                        if self._audit_repository is not None:
+                            self._audit_repository.insert(
+                                AuditRecord(
+                                    occurred_at=datetime.now(UTC),
+                                    actor="execution_engine",
+                                    event_type="execution.live_trade",
+                                    decision="rejected",
+                                    payload={
+                                        "reason": "missing_executor",
+                                        "cycle": event.cycle,
+                                    },
+                                )
+                            )
+                        continue
+
+                    if self._kill_switch is not None and self._kill_switch.is_active:
+                        _LOG.warning(
+                            "live_trade_skipped_kill_switch",
+                            cycle=event.cycle,
+                            updated_pair=event.updated_pair,
+                            reason=self._kill_switch.reason,
+                        )
+                        if self._audit_repository is not None:
+                            self._audit_repository.insert(
+                                AuditRecord(
+                                    occurred_at=datetime.now(UTC),
+                                    actor="risk_manager",
+                                    event_type="risk.kill_switch",
+                                    decision="rejected",
+                                    payload={
+                                        "reason": self._kill_switch.reason or "manual",
+                                        "cycle": event.cycle,
+                                    },
+                                )
+                            )
+                        continue
+
+                    if (
+                        self._stop_conditions_guard is not None
+                        and self._stop_conditions_guard.is_halted
+                    ):
+                        _LOG.warning(
+                            "live_trade_skipped_stop_condition_halt",
+                            cycle=event.cycle,
+                            updated_pair=event.updated_pair,
+                            reason=self._stop_conditions_guard.halted_reason,
+                        )
+                        if self._audit_repository is not None:
+                            self._audit_repository.insert(
+                                AuditRecord(
+                                    occurred_at=datetime.now(UTC),
+                                    actor="risk_manager",
+                                    event_type="risk.stop_condition",
+                                    decision="rejected",
+                                    payload={
+                                        "reason": self._stop_conditions_guard.halted_reason
+                                        or "halted",
+                                        "cycle": event.cycle,
+                                    },
+                                )
+                            )
+                        continue
+
+                    if self._loss_limit_guard is not None and self._loss_limit_guard.is_halted:
+                        _LOG.warning(
+                            "live_trade_skipped_loss_limit_halted",
+                            cycle=event.cycle,
+                            updated_pair=event.updated_pair,
+                            reason=self._loss_limit_guard.halted_reason,
+                        )
+                        if self._audit_repository is not None:
+                            self._audit_repository.insert(
+                                AuditRecord(
+                                    occurred_at=datetime.now(UTC),
+                                    actor="risk_manager",
+                                    event_type="risk.loss_limit",
+                                    decision="rejected",
+                                    payload={
+                                        "reason": self._loss_limit_guard.halted_reason or "halted",
+                                        "cycle": event.cycle,
+                                    },
+                                )
+                            )
+                        continue
+
+                    if self._pre_trade_validator is not None and self._balance_provider is not None:
+                        required_balances = {self._quote_balance_asset: event.allocated_capital}
+                        balances = {
+                            asset.upper(): amount
+                            for asset, amount in self._balance_provider().items()
+                        }
+                        if not self._pre_trade_validator.validate(
+                            balances_by_asset=balances,
+                            required_by_asset=required_balances,
+                        ):
+                            _LOG.warning(
+                                "live_trade_skipped_pre_trade_validation",
+                                cycle=event.cycle,
+                                updated_pair=event.updated_pair,
+                                required_by_asset=required_balances,
+                            )
+                            if self._audit_repository is not None:
+                                self._audit_repository.insert(
+                                    AuditRecord(
+                                        occurred_at=datetime.now(UTC),
+                                        actor="risk_manager",
+                                        event_type="risk.pre_trade_validation",
+                                        decision="rejected",
+                                        payload={
+                                            "cycle": event.cycle,
+                                            "required_by_asset": {
+                                                key: required_balances[key]
+                                                for key in required_balances
+                                            },
+                                        },
+                                    )
+                                )
+                            continue
+
+                    exposure_by_asset = self._exposure_for_event(event)
+                    if (
+                        self._trade_limits_guard is not None
+                        and not self._trade_limits_guard.is_trade_allowed(exposure_by_asset)
+                    ):
+                        _LOG.warning(
+                            "live_trade_skipped_trade_limits",
+                            cycle=event.cycle,
+                            updated_pair=event.updated_pair,
+                            exposure_by_asset=exposure_by_asset,
+                        )
+                        if self._audit_repository is not None:
+                            self._audit_repository.insert(
+                                AuditRecord(
+                                    occurred_at=datetime.now(UTC),
+                                    actor="risk_manager",
+                                    event_type="risk.trade_limits",
+                                    decision="rejected",
+                                    payload={
+                                        "cycle": event.cycle,
+                                        "exposure_by_asset": {
+                                            key: exposure_by_asset[key] for key in exposure_by_asset
+                                        },
+                                    },
+                                )
+                            )
+                        continue
+
+                    if self._trade_limits_guard is not None:
+                        self._trade_limits_guard.open_trade(exposure_by_asset)
+
+                    try:
+                        outcome = await self._opportunity_executor(event)
+                    except Exception as exc:
+                        if self._trade_limits_guard is not None:
+                            self._trade_limits_guard.close_trade(exposure_by_asset)
+
+                        dispatch_alert_nowait(
+                            self._alert_notifier,
+                            category="system",
+                            severity="critical",
+                            title="Critical execution exception",
+                            message="Unhandled exception raised by opportunity executor.",
+                            details={
+                                "cycle": event.cycle,
+                                "updated_pair": event.updated_pair,
+                                "error": str(exc),
+                            },
+                        )
+
+                        if self._stop_conditions_guard is not None:
+                            self._stop_conditions_guard.register_failure()
+                            if self._stop_conditions_guard.is_halted:
+                                if (
+                                    self._kill_switch is not None
+                                    and not self._kill_switch.is_active
+                                ):
+                                    self._kill_switch.activate(
+                                        reason=self._stop_conditions_guard.halted_reason
+                                        or "stop_conditions_halted",
+                                    )
+                                _LOG.warning(
+                                    "stop_condition_halt_triggered",
+                                    reason=self._stop_conditions_guard.halted_reason,
+                                    cycle=event.cycle,
+                                    updated_pair=event.updated_pair,
+                                )
+
+                        _LOG.exception(
+                            "live_trade_execution_failed",
+                            cycle=event.cycle,
+                            updated_pair=event.updated_pair,
+                        )
+                        if self._audit_repository is not None:
+                            self._audit_repository.insert(
+                                AuditRecord(
+                                    occurred_at=datetime.now(UTC),
+                                    actor="execution_engine",
+                                    event_type="execution.live_trade",
+                                    decision="error",
+                                    payload={
+                                        "cycle": event.cycle,
+                                        "updated_pair": event.updated_pair,
+                                        "error": str(exc),
+                                    },
+                                )
+                            )
+                        continue
+
+                    if self._stop_conditions_guard is not None:
+                        self._stop_conditions_guard.register_success()
+
+                    realized_pnl: float | None
+                    close_trade = True
+                    if isinstance(outcome, ExecutionOutcome):
+                        realized_pnl = outcome.realized_pnl
+                        close_trade = outcome.close_trade
+                    else:
+                        realized_pnl = outcome
+
+                    if realized_pnl is not None and self._loss_limit_guard is not None:
+                        self._loss_limit_guard.register_realized_pnl(realized_pnl)
+                        if self._loss_limit_guard.is_halted:
+                            _LOG.warning(
+                                "loss_limit_halt_triggered",
+                                reason=self._loss_limit_guard.halted_reason,
+                                cumulative_pnl=self._loss_limit_guard.cumulative_pnl,
+                            )
+
+                    if self._trade_limits_guard is not None and close_trade:
+                        self._trade_limits_guard.close_trade(exposure_by_asset)
+
+                    if self._audit_repository is not None:
+                        self._audit_repository.insert(
+                            AuditRecord(
+                                occurred_at=datetime.now(UTC),
+                                actor="execution_engine",
+                                event_type="execution.live_trade",
+                                decision="approved",
+                                payload={
+                                    "cycle": event.cycle,
+                                    "updated_pair": event.updated_pair,
+                                    "realized_pnl": realized_pnl,
+                                    "close_trade": close_trade,
+                                },
+                            )
+                        )
+
+            await self._snapshot_writer.enqueue(
+                MarketSnapshot(
+                    snapshot_at=datetime.now(UTC),
+                    symbol=delta.symbol,
+                    source="kraken_ws",
+                    payload=message.payload,
+                    latency_ms=source_latency_ms,
+                )
+            )

src/arbitrade/market_data/order_book.py

@@ -0,0 +1,104 @@
+from __future__ import annotations
+
+import re
+from collections.abc import Iterable
+from dataclasses import dataclass
+from datetime import UTC, datetime
+
+from sortedcontainers import SortedDict
+
+from arbitrade.exchange.models import BookLevel
+
+ZERO_CLEAN_RE = re.compile(r"^0+", re.ASCII)
+
+
+def _normalize_price_for_checksum(value: float) -> str:
+    text = f"{value:.10f}".replace(".", "")
+    text = text.rstrip("0")
+    stripped = ZERO_CLEAN_RE.sub("", text)
+    return stripped or "0"
+
+
+def _normalize_volume_for_checksum(value: float) -> str:
+    text = f"{value:.10f}".replace(".", "")
+    text = text.rstrip("0")
+    stripped = ZERO_CLEAN_RE.sub("", text)
+    return stripped or "0"
+
+
+@dataclass(slots=True)
+class BookView:
+    best_bid: BookLevel | None
+    best_ask: BookLevel | None
+    updated_at: datetime
+
+
+class OrderBook:
+    def __init__(self) -> None:
+        self._bids: SortedDict[float, float] = SortedDict()
+        self._asks: SortedDict[float, float] = SortedDict()
+        self._updated_at: datetime = datetime.now(UTC)
+
+    @property
+    def updated_at(self) -> datetime:
+        return self._updated_at
+
+    def apply_bids(self, updates: Iterable[BookLevel]) -> None:
+        for level in updates:
+            if level.volume <= 0:
+                self._bids.pop(level.price, None)
+            else:
+                self._bids[level.price] = level.volume
+        self._updated_at = datetime.now(UTC)
+
+    def apply_asks(self, updates: Iterable[BookLevel]) -> None:
+        for level in updates:
+            if level.volume <= 0:
+                self._asks.pop(level.price, None)
+            else:
+                self._asks[level.price] = level.volume
+        self._updated_at = datetime.now(UTC)
+
+    def best_bid(self) -> BookLevel | None:
+        if not self._bids:
+            return None
+        price = self._bids.peekitem(-1)[0]
+        return BookLevel(price=price, volume=self._bids[price])
+
+    def best_ask(self) -> BookLevel | None:
+        if not self._asks:
+            return None
+        price = self._asks.peekitem(0)[0]
+        return BookLevel(price=price, volume=self._asks[price])
+
+    def snapshot(self) -> BookView:
+        return BookView(
+            best_bid=self.best_bid(),
+            best_ask=self.best_ask(),
+            updated_at=self._updated_at,
+        )
+
+    def top_levels(self, depth: int = 10) -> tuple[list[BookLevel], list[BookLevel]]:
+        bid_keys = list(self._bids.keys())
+        ask_keys = list(self._asks.keys())
+
+        bids = [
+            BookLevel(price=price, volume=self._bids[price])
+            for price in reversed(bid_keys[-depth:])
+        ]
+        asks = [BookLevel(price=price, volume=self._asks[price]) for price in ask_keys[:depth]]
+        return bids, asks
+
+    def compute_checksum(self, depth: int = 10) -> int:
+        bids, asks = self.top_levels(depth)
+        combined: list[str] = []
+        for level in bids:
+            combined.append(_normalize_price_for_checksum(level.price))
+            combined.append(_normalize_volume_for_checksum(level.volume))
+        for level in asks:
+            combined.append(_normalize_price_for_checksum(level.price))
+            combined.append(_normalize_volume_for_checksum(level.volume))
+
+        import zlib
+
+        return zlib.crc32("".join(combined).encode("utf-8"))

src/arbitrade/metrics.py

@@ -0,0 +1,132 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import datetime
+
+from arbitrade.storage.db import DuckDBStore
+
+
+@dataclass(frozen=True, slots=True)
+class PerformanceMetrics:
+    realized_pnl_usd: float
+    win_rate: float | None
+    avg_trade_duration_seconds: float | None
+    opportunities_per_minute: float | None
+    fill_rate: float | None
+    latency_p50_seconds: float | None
+    latency_p95_seconds: float | None
+    latency_p99_seconds: float | None
+
+
+class MetricsCalculator:
+    def __init__(self, store: DuckDBStore) -> None:
+        self._store = store
+
+    def compute(self) -> PerformanceMetrics:
+        with self._store.connect() as conn:
+            trade_metrics = conn.execute("""
+                SELECT
+                    COALESCE(SUM(COALESCE(realized_pnl, 0)), 0) AS realized_pnl_usd,
+                    COUNT(*) AS total_trades,
+                    SUM(CASE WHEN realized_pnl > 0 THEN 1 ELSE 0 END) AS winning_trades,
+                    AVG(EPOCH(finished_at) - EPOCH(started_at)) AS avg_trade_duration_seconds,
+                    quantile_cont(
+                        EPOCH(finished_at) - EPOCH(started_at),
+                        0.50
+                    ) AS latency_p50_seconds,
+                    quantile_cont(
+                        EPOCH(finished_at) - EPOCH(started_at),
+                        0.95
+                    ) AS latency_p95_seconds,
+                    quantile_cont(
+                        EPOCH(finished_at) - EPOCH(started_at),
+                        0.99
+                    ) AS latency_p99_seconds
+                FROM trades
+                WHERE finished_at IS NOT NULL
+                """).fetchone()
+
+            opportunity_metrics = conn.execute("""
+                SELECT
+                    COUNT(*) AS opportunity_count,
+                    MIN(detected_at) AS first_detected_at,
+                    MAX(detected_at) AS last_detected_at
+                FROM opportunities
+                """).fetchone()
+
+            fill_metrics = conn.execute("""
+                SELECT AVG(filled_volume / volume) AS fill_rate
+                FROM orders
+                WHERE volume > 0 AND filled_volume IS NOT NULL
+                """).fetchone()
+
+        realized_pnl_usd = (
+            float(trade_metrics[0]) if trade_metrics and trade_metrics[0] is not None else 0.0
+        )
+        total_trades = (
+            int(trade_metrics[1]) if trade_metrics and trade_metrics[1] is not None else 0
+        )
+        winning_trades = (
+            int(trade_metrics[2]) if trade_metrics and trade_metrics[2] is not None else 0
+        )
+        win_rate = winning_trades / total_trades if total_trades > 0 else None
+
+        avg_trade_duration_seconds = (
+            float(trade_metrics[3]) if trade_metrics and trade_metrics[3] is not None else None
+        )
+
+        opportunity_count = (
+            int(opportunity_metrics[0])
+            if opportunity_metrics is not None and opportunity_metrics[0] is not None
+            else 0
+        )
+        first_detected_at = (
+            opportunity_metrics[1]
+            if opportunity_metrics is not None and isinstance(opportunity_metrics[1], datetime)
+            else None
+        )
+        last_detected_at = (
+            opportunity_metrics[2]
+            if opportunity_metrics is not None and isinstance(opportunity_metrics[2], datetime)
+            else None
+        )
+
+        opportunities_per_minute: float | None
+        if (
+            opportunity_count >= 2
+            and first_detected_at is not None
+            and last_detected_at is not None
+        ):
+            span_seconds = (last_detected_at - first_detected_at).total_seconds()
+            opportunities_per_minute = (
+                opportunity_count / (span_seconds / 60.0)
+                if span_seconds > 0.0
+                else float(opportunity_count)
+            )
+        elif opportunity_count == 1:
+            opportunities_per_minute = 60.0
+        else:
+            opportunities_per_minute = None
+
+        fill_rate = float(fill_metrics[0]) if fill_metrics and fill_metrics[0] is not None else None
+
+        latency_p50_seconds = (
+            float(trade_metrics[4]) if trade_metrics and trade_metrics[4] is not None else None
+        )
+        latency_p95_seconds = (
+            float(trade_metrics[5]) if trade_metrics and trade_metrics[5] is not None else None
+        )
+        latency_p99_seconds = (
+            float(trade_metrics[6]) if trade_metrics and trade_metrics[6] is not None else None
+        )
+
+        return PerformanceMetrics(
+            realized_pnl_usd=realized_pnl_usd,
+            win_rate=win_rate,
+            avg_trade_duration_seconds=avg_trade_duration_seconds,
+            opportunities_per_minute=opportunities_per_minute,
+            fill_rate=fill_rate,
+            latency_p50_seconds=latency_p50_seconds,
+            latency_p95_seconds=latency_p95_seconds,
+            latency_p99_seconds=latency_p99_seconds,
+        )

src/arbitrade/perf/__init__.py

@@ -0,0 +1,4 @@
+from arbitrade.perf.guardrails import evaluate_guardrails
+from arbitrade.perf.latency import run_latency_profile
+
+__all__ = ["run_latency_profile", "evaluate_guardrails"]

src/arbitrade/perf/guardrails.py

@@ -0,0 +1,80 @@
+from __future__ import annotations
+
+
+def evaluate_guardrails(
+    *,
+    baseline: dict[str, object],
+    current: dict[str, object],
+    thresholds: dict[str, object],
+) -> list[str]:
+    failures: list[str] = []
+
+    baseline_scenarios = baseline.get("scenarios")
+    current_scenarios = current.get("scenarios")
+    if not isinstance(baseline_scenarios, dict) or not isinstance(current_scenarios, dict):
+        return ["invalid profile payload: missing scenarios map"]
+
+    default_thresholds = thresholds.get("default")
+    if not isinstance(default_thresholds, dict):
+        default_thresholds = {"p95_ms": 2.5, "p99_ms": 3.0}
+
+    scenario_thresholds = thresholds.get("scenarios")
+    if not isinstance(scenario_thresholds, dict):
+        scenario_thresholds = {}
+
+    for scenario, baseline_payload in baseline_scenarios.items():
+        current_payload = current_scenarios.get(scenario)
+        if not isinstance(baseline_payload, dict) or not isinstance(current_payload, dict):
+            failures.append(f"missing scenario in current profile: {scenario}")
+            continue
+
+        baseline_stages = baseline_payload.get("stages")
+        current_stages = current_payload.get("stages")
+        if not isinstance(baseline_stages, dict) or not isinstance(current_stages, dict):
+            failures.append(f"missing stages map for scenario: {scenario}")
+            continue
+
+        scenario_config = scenario_thresholds.get(scenario)
+        if not isinstance(scenario_config, dict):
+            scenario_config = {}
+
+        for stage, baseline_stage in baseline_stages.items():
+            current_stage = current_stages.get(stage)
+            if not isinstance(baseline_stage, dict) or not isinstance(current_stage, dict):
+                failures.append(f"missing stage in current profile: {scenario}.{stage}")
+                continue
+
+            for percentile_key in ("p95_ms", "p99_ms"):
+                threshold_ratio_raw = scenario_config.get(
+                    percentile_key,
+                    default_thresholds.get(percentile_key, 3.0),
+                )
+                threshold_ratio = (
+                    float(threshold_ratio_raw)
+                    if isinstance(threshold_ratio_raw, int | float)
+                    else 3.0
+                )
+
+                base_value_raw = baseline_stage.get(percentile_key)
+                current_value_raw = current_stage.get(percentile_key)
+                if not isinstance(base_value_raw, int | float) or not isinstance(
+                    current_value_raw, int | float
+                ):
+                    failures.append(
+                        f"invalid percentile value: {scenario}.{stage}.{percentile_key}"
+                    )
+                    continue
+
+                base_value = float(base_value_raw)
+                current_value = float(current_value_raw)
+                # Avoid divide-by-zero while still preserving strict checks.
+                max_allowed = max(base_value * threshold_ratio, 0.001)
+                if current_value > max_allowed:
+                    failures.append(
+                        f"latency regression: {scenario}.{stage}.{percentile_key} "
+                        f"current={current_value:.4f}ms "
+                        f"baseline={base_value:.4f}ms "
+                        f"allowed={max_allowed:.4f}ms"
+                    )
+
+    return failures

src/arbitrade/perf/latency.py

@@ -0,0 +1,195 @@
+from __future__ import annotations
+
+from collections.abc import Callable
+from dataclasses import dataclass
+from time import perf_counter_ns
+
+import orjson
+
+
+@dataclass(frozen=True, slots=True)
+class PercentileSummary:
+    p50_ms: float
+    p95_ms: float
+    p99_ms: float
+
+
+@dataclass(frozen=True, slots=True)
+class ScenarioProfile:
+    scenario: str
+    iterations: int
+    stages: dict[str, PercentileSummary]
+
+
+def _percentile(samples: list[float], percentile: float) -> float:
+    if not samples:
+        return 0.0
+    ordered = sorted(samples)
+    if percentile <= 0.0:
+        return ordered[0]
+    if percentile >= 100.0:
+        return ordered[-1]
+    rank = (len(ordered) - 1) * (percentile / 100.0)
+    lower = int(rank)
+    upper = min(lower + 1, len(ordered) - 1)
+    weight = rank - lower
+    return ordered[lower] * (1.0 - weight) + ordered[upper] * weight
+
+
+def _summarize(samples: list[float]) -> PercentileSummary:
+    return PercentileSummary(
+        p50_ms=_percentile(samples, 50.0),
+        p95_ms=_percentile(samples, 95.0),
+        p99_ms=_percentile(samples, 99.0),
+    )
+
+
+def _ingest_stage(raw_payload: bytes, state: dict[str, float]) -> None:
+    parsed = orjson.loads(raw_payload)
+    bids = parsed.get("bids", [])
+    asks = parsed.get("asks", [])
+    for price, volume in bids[:4]:
+        state[str(price)] = float(volume)
+    for price, volume in asks[:4]:
+        state[str(price)] = float(volume)
+
+
+def _detect_stage(values: list[float], cycles: int) -> float:
+    best = 0.0
+    size = len(values)
+    for idx in range(cycles):
+        a = values[idx % size]
+        b = values[(idx + 3) % size]
+        c = values[(idx + 7) % size]
+        gross = (a / b) * c
+        net = gross * 0.9975
+        if net > best:
+            best = net
+    return best
+
+
+def _risk_stage(net_edge: float, capital: float) -> float:
+    if net_edge < 1.0002:
+        return 0.0
+    if capital > 500.0:
+        capital = 500.0
+    return capital * min(net_edge - 1.0, 0.02)
+
+
+def _execution_stage(planned_pnl: float, order_id: int) -> None:
+    payload = {
+        "order_id": order_id,
+        "planned_pnl": planned_pnl,
+        "legs": [
+            {"pair": "BTC/USD", "side": "buy", "qty": 0.01},
+            {"pair": "ETH/BTC", "side": "buy", "qty": 0.1},
+            {"pair": "ETH/USD", "side": "sell", "qty": 0.1},
+        ],
+    }
+    _ = orjson.dumps(payload)
+
+
+def _run_scenario(
+    name: str,
+    iterations: int,
+    detect_cycles: int,
+    reconnect_every: int,
+) -> ScenarioProfile:
+    payloads = [
+        orjson.dumps(
+            {
+                "symbol": "BTC/USD",
+                "bids": [[100000.0 + i, 0.2 + (i % 5) * 0.01] for i in range(12)],
+                "asks": [[100001.0 + i, 0.2 + (i % 7) * 0.01] for i in range(12)],
+            }
+        )
+        for _ in range(5)
+    ]
+    value_series = [1.0 + (idx % 31) * 0.0007 for idx in range(128)]
+    order_state: dict[str, float] = {}
+
+    ingest_ms: list[float] = []
+    detect_ms: list[float] = []
+    risk_ms: list[float] = []
+    execution_ms: list[float] = []
+    end_to_end_ms: list[float] = []
+
+    for idx in range(iterations):
+        start_ns = perf_counter_ns()
+        payload = payloads[idx % len(payloads)]
+
+        t0 = perf_counter_ns()
+        _ingest_stage(payload, order_state)
+        if reconnect_every > 0 and idx > 0 and idx % reconnect_every == 0:
+            order_state.clear()
+        t1 = perf_counter_ns()
+
+        net_edge = _detect_stage(value_series, detect_cycles)
+        t2 = perf_counter_ns()
+
+        planned = _risk_stage(net_edge, capital=100.0 + (idx % 50))
+        t3 = perf_counter_ns()
+
+        _execution_stage(planned, order_id=idx)
+        t4 = perf_counter_ns()
+
+        ingest_ms.append((t1 - t0) / 1_000_000.0)
+        detect_ms.append((t2 - t1) / 1_000_000.0)
+        risk_ms.append((t3 - t2) / 1_000_000.0)
+        execution_ms.append((t4 - t3) / 1_000_000.0)
+        end_to_end_ms.append((t4 - start_ns) / 1_000_000.0)
+
+    return ScenarioProfile(
+        scenario=name,
+        iterations=iterations,
+        stages={
+            "ingest": _summarize(ingest_ms),
+            "detect": _summarize(detect_ms),
+            "risk": _summarize(risk_ms),
+            "execution": _summarize(execution_ms),
+            "end_to_end": _summarize(end_to_end_ms),
+        },
+    )
+
+
+def run_latency_profile(iterations: int = 600) -> dict[str, object]:
+    scenarios: list[Callable[[], ScenarioProfile]] = [
+        lambda: _run_scenario(
+            name="book_update_burst",
+            iterations=iterations,
+            detect_cycles=32,
+            reconnect_every=0,
+        ),
+        lambda: _run_scenario(
+            name="execution_spike",
+            iterations=iterations,
+            detect_cycles=96,
+            reconnect_every=0,
+        ),
+        lambda: _run_scenario(
+            name="reconnect_storm",
+            iterations=iterations,
+            detect_cycles=48,
+            reconnect_every=20,
+        ),
+    ]
+
+    result: dict[str, object] = {"iterations": iterations, "scenarios": {}}
+    scenario_map = result["scenarios"]
+    assert isinstance(scenario_map, dict)
+
+    for scenario in scenarios:
+        profile = scenario()
+        scenario_map[profile.scenario] = {
+            "iterations": profile.iterations,
+            "stages": {
+                stage: {
+                    "p50_ms": summary.p50_ms,
+                    "p95_ms": summary.p95_ms,
+                    "p99_ms": summary.p99_ms,
+                }
+                for stage, summary in profile.stages.items()
+            },
+        }
+
+    return result

src/arbitrade/risk/__init__.py

@@ -0,0 +1,15 @@
+"""Risk management helpers."""
+
+from arbitrade.risk.kill_switch import KillSwitch
+from arbitrade.risk.loss_limits import LossLimitGuard
+from arbitrade.risk.pre_trade import PreTradeValidator
+from arbitrade.risk.stop_conditions import StopConditionsGuard
+from arbitrade.risk.trade_limits import TradeLimitsGuard
+
+__all__ = [
+    "LossLimitGuard",
+    "TradeLimitsGuard",
+    "PreTradeValidator",
+    "KillSwitch",
+    "StopConditionsGuard",
+]

src/arbitrade/risk/kill_switch.py

@@ -0,0 +1,23 @@
+from __future__ import annotations
+
+
+class KillSwitch:
+    def __init__(self, *, active: bool = False, reason: str | None = None) -> None:
+        self._active = active
+        self._reason = reason or ("manual" if active else None)
+
+    @property
+    def is_active(self) -> bool:
+        return self._active
+
+    @property
+    def reason(self) -> str | None:
+        return self._reason
+
+    def activate(self, *, reason: str = "manual") -> None:
+        self._active = True
+        self._reason = reason
+
+    def deactivate(self) -> None:
+        self._active = False
+        self._reason = None

src/arbitrade/risk/loss_limits.py

@@ -0,0 +1,90 @@
+from __future__ import annotations
+
+from datetime import UTC, date, datetime
+
+from arbitrade.alerting.notifier import SupportsAlerts, dispatch_alert_nowait
+
+
+class LossLimitGuard:
+    def __init__(
+        self,
+        *,
+        daily_loss_limit: float | None = None,
+        cumulative_loss_limit: float | None = None,
+        alert_notifier: SupportsAlerts | None = None,
+    ) -> None:
+        self._daily_loss_limit = daily_loss_limit
+        self._cumulative_loss_limit = cumulative_loss_limit
+
+        if self._daily_loss_limit is not None and self._daily_loss_limit <= 0.0:
+            raise ValueError("daily_loss_limit must be > 0.0")
+        if self._cumulative_loss_limit is not None and self._cumulative_loss_limit <= 0.0:
+            raise ValueError("cumulative_loss_limit must be > 0.0")
+
+        self._cumulative_pnl = 0.0
+        self._daily_pnl: dict[date, float] = {}
+        self._halted_reason: str | None = None
+        self._alert_notifier = alert_notifier
+
+    @property
+    def cumulative_pnl(self) -> float:
+        return self._cumulative_pnl
+
+    @property
+    def halted_reason(self) -> str | None:
+        return self._halted_reason
+
+    @property
+    def is_halted(self) -> bool:
+        return self._halted_reason is not None
+
+    def daily_pnl(self, day: date) -> float:
+        return self._daily_pnl.get(day, 0.0)
+
+    def register_realized_pnl(self, pnl: float, *, at: datetime | None = None) -> None:
+        if self.is_halted:
+            return
+
+        timestamp = at or datetime.now(UTC)
+        day_key = timestamp.date()
+
+        self._cumulative_pnl += pnl
+        self._daily_pnl[day_key] = self._daily_pnl.get(day_key, 0.0) + pnl
+
+        if (
+            self._daily_loss_limit is not None
+            and self._daily_pnl[day_key] <= -self._daily_loss_limit
+        ):
+            self._halted_reason = "daily_loss_limit_breached"
+            dispatch_alert_nowait(
+                self._alert_notifier,
+                category="threshold",
+                severity="critical",
+                title="Daily loss limit breached",
+                message="Trading halted because daily realized PnL crossed configured loss limit.",
+                details={
+                    "daily_pnl": f"{self._daily_pnl[day_key]}",
+                    "daily_loss_limit": f"{self._daily_loss_limit}",
+                },
+            )
+            return
+
+        if (
+            self._cumulative_loss_limit is not None
+            and self._cumulative_pnl <= -self._cumulative_loss_limit
+        ):
+            self._halted_reason = "cumulative_loss_limit_breached"
+            dispatch_alert_nowait(
+                self._alert_notifier,
+                category="threshold",
+                severity="critical",
+                title="Cumulative loss limit breached",
+                message=(
+                    "Trading halted because cumulative realized PnL crossed "
+                    "configured loss limit."
+                ),
+                details={
+                    "cumulative_pnl": f"{self._cumulative_pnl}",
+                    "cumulative_loss_limit": f"{self._cumulative_loss_limit}",
+                },
+            )

src/arbitrade/risk/pre_trade.py

@@ -0,0 +1,43 @@
+from __future__ import annotations
+
+from collections.abc import Mapping
+
+
+class PreTradeValidator:
+    def __init__(
+        self,
+        *,
+        min_order_size_by_asset: Mapping[str, float] | None = None,
+    ) -> None:
+        self._min_order_size_by_asset = {
+            asset.upper(): float(value) for asset, value in (min_order_size_by_asset or {}).items()
+        }
+
+        for value in self._min_order_size_by_asset.values():
+            if value <= 0.0:
+                raise ValueError("minimum order size must be > 0.0")
+
+    def validate(
+        self,
+        *,
+        balances_by_asset: Mapping[str, float],
+        required_by_asset: Mapping[str, float],
+    ) -> bool:
+        # Minimum order size checks first to fail fast on structural invalid sizes.
+        for asset, required in required_by_asset.items():
+            if required <= 0.0:
+                continue
+
+            min_size = self._min_order_size_by_asset.get(asset.upper())
+            if min_size is not None and required < min_size:
+                return False
+
+        # Balance checks ensure required quantity is currently available.
+        for asset, required in required_by_asset.items():
+            if required <= 0.0:
+                continue
+            available = balances_by_asset.get(asset.upper(), 0.0)
+            if available < required:
+                return False
+
+        return True

src/arbitrade/risk/stop_conditions.py

@@ -0,0 +1,109 @@
+from __future__ import annotations
+
+from arbitrade.alerting.notifier import SupportsAlerts, dispatch_alert_nowait
+
+
+class StopConditionsGuard:
+    def __init__(
+        self,
+        *,
+        max_source_latency_ms: float | None = None,
+        max_apply_latency_ms: float | None = None,
+        max_consecutive_failures: int | None = None,
+        alert_notifier: SupportsAlerts | None = None,
+    ) -> None:
+        if max_source_latency_ms is not None and max_source_latency_ms <= 0.0:
+            raise ValueError("max_source_latency_ms must be > 0.0")
+        if max_apply_latency_ms is not None and max_apply_latency_ms <= 0.0:
+            raise ValueError("max_apply_latency_ms must be > 0.0")
+        if max_consecutive_failures is not None and max_consecutive_failures <= 0:
+            raise ValueError("max_consecutive_failures must be > 0")
+
+        self._max_source_latency_ms = max_source_latency_ms
+        self._max_apply_latency_ms = max_apply_latency_ms
+        self._max_consecutive_failures = max_consecutive_failures
+
+        self._consecutive_failures = 0
+        self._halted_reason: str | None = None
+        self._alert_notifier = alert_notifier
+
+    @property
+    def halted_reason(self) -> str | None:
+        return self._halted_reason
+
+    @property
+    def is_halted(self) -> bool:
+        return self._halted_reason is not None
+
+    @property
+    def consecutive_failures(self) -> int:
+        return self._consecutive_failures
+
+    def observe_latency(
+        self,
+        *,
+        source_latency_ms: float | None,
+        apply_latency_ms: float,
+    ) -> None:
+        if self.is_halted:
+            return
+
+        if (
+            self._max_source_latency_ms is not None
+            and source_latency_ms is not None
+            and source_latency_ms > self._max_source_latency_ms
+        ):
+            self._halted_reason = "source_latency_limit_breached"
+            dispatch_alert_nowait(
+                self._alert_notifier,
+                category="threshold",
+                severity="critical",
+                title="Source latency limit breached",
+                message="Trading halted because source latency exceeded configured limit.",
+                details={
+                    "source_latency_ms": f"{source_latency_ms}",
+                    "max_source_latency_ms": f"{self._max_source_latency_ms}",
+                },
+            )
+            return
+
+        if self._max_apply_latency_ms is not None and apply_latency_ms > self._max_apply_latency_ms:
+            self._halted_reason = "apply_latency_limit_breached"
+            dispatch_alert_nowait(
+                self._alert_notifier,
+                category="threshold",
+                severity="critical",
+                title="Apply latency limit breached",
+                message="Trading halted because apply latency exceeded configured limit.",
+                details={
+                    "apply_latency_ms": f"{apply_latency_ms}",
+                    "max_apply_latency_ms": f"{self._max_apply_latency_ms}",
+                },
+            )
+
+    def register_failure(self) -> None:
+        if self.is_halted:
+            return
+
+        self._consecutive_failures += 1
+        if (
+            self._max_consecutive_failures is not None
+            and self._consecutive_failures >= self._max_consecutive_failures
+        ):
+            self._halted_reason = "consecutive_failures_limit_breached"
+            dispatch_alert_nowait(
+                self._alert_notifier,
+                category="threshold",
+                severity="critical",
+                title="Consecutive failures limit breached",
+                message="Trading halted because consecutive failures exceeded configured limit.",
+                details={
+                    "consecutive_failures": f"{self._consecutive_failures}",
+                    "max_consecutive_failures": f"{self._max_consecutive_failures}",
+                },
+            )
+
+    def register_success(self) -> None:
+        if self.is_halted:
+            return
+        self._consecutive_failures = 0

src/arbitrade/risk/trade_limits.py

@@ -0,0 +1,98 @@
+from __future__ import annotations
+
+from collections.abc import Mapping
+
+from arbitrade.alerting.notifier import SupportsAlerts, dispatch_alert_nowait
+
+
+class TradeLimitsGuard:
+    def __init__(
+        self,
+        *,
+        max_concurrent_trades: int | None = None,
+        max_exposure_per_asset: float | None = None,
+        alert_notifier: SupportsAlerts | None = None,
+    ) -> None:
+        if max_concurrent_trades is not None and max_concurrent_trades <= 0:
+            raise ValueError("max_concurrent_trades must be > 0")
+        if max_exposure_per_asset is not None and max_exposure_per_asset <= 0.0:
+            raise ValueError("max_exposure_per_asset must be > 0.0")
+
+        self._max_concurrent_trades = max_concurrent_trades
+        self._max_exposure_per_asset = max_exposure_per_asset
+        self._active_trades = 0
+        self._asset_exposure: dict[str, float] = {}
+        self._alert_notifier = alert_notifier
+
+    @property
+    def active_trades(self) -> int:
+        return self._active_trades
+
+    def exposure_for_asset(self, asset: str) -> float:
+        return self._asset_exposure.get(asset.upper(), 0.0)
+
+    def is_trade_allowed(self, exposure_by_asset: Mapping[str, float]) -> bool:
+        if (
+            self._max_concurrent_trades is not None
+            and self._active_trades >= self._max_concurrent_trades
+        ):
+            dispatch_alert_nowait(
+                self._alert_notifier,
+                category="threshold",
+                severity="warning",
+                title="Concurrent trade limit reached",
+                message="Trade rejected by concurrent trade cap.",
+                details={
+                    "active_trades": f"{self._active_trades}",
+                    "max_concurrent_trades": f"{self._max_concurrent_trades}",
+                },
+            )
+            return False
+
+        if self._max_exposure_per_asset is None:
+            return True
+
+        for asset, exposure in exposure_by_asset.items():
+            if exposure <= 0.0:
+                continue
+            key = asset.upper()
+            next_exposure = self._asset_exposure.get(key, 0.0) + exposure
+            if next_exposure > self._max_exposure_per_asset:
+                dispatch_alert_nowait(
+                    self._alert_notifier,
+                    category="threshold",
+                    severity="warning",
+                    title="Asset exposure limit reached",
+                    message="Trade rejected by per-asset exposure cap.",
+                    details={
+                        "asset": key,
+                        "next_exposure": f"{next_exposure}",
+                        "max_exposure_per_asset": f"{self._max_exposure_per_asset}",
+                    },
+                )
+                return False
+
+        return True
+
+    def open_trade(self, exposure_by_asset: Mapping[str, float]) -> None:
+        self._active_trades += 1
+        for asset, exposure in exposure_by_asset.items():
+            if exposure <= 0.0:
+                continue
+            key = asset.upper()
+            self._asset_exposure[key] = self._asset_exposure.get(key, 0.0) + exposure
+
+    def close_trade(self, exposure_by_asset: Mapping[str, float]) -> None:
+        if self._active_trades > 0:
+            self._active_trades -= 1
+
+        for asset, exposure in exposure_by_asset.items():
+            if exposure <= 0.0:
+                continue
+            key = asset.upper()
+            current = self._asset_exposure.get(key, 0.0)
+            next_exposure = max(current - exposure, 0.0)
+            if next_exposure == 0.0:
+                self._asset_exposure.pop(key, None)
+            else:
+                self._asset_exposure[key] = next_exposure

src/arbitrade/runtime/__init__.py

@@ -0,0 +1,15 @@
+"""Runtime lifecycle and recovery helpers."""
+
+from arbitrade.runtime.lifecycle import (
+    RuntimeRecoveryReport,
+    graceful_shutdown,
+    persist_runtime_snapshot,
+    restore_runtime_state,
+)
+
+__all__ = [
+    "RuntimeRecoveryReport",
+    "graceful_shutdown",
+    "persist_runtime_snapshot",
+    "restore_runtime_state",
+]

src/arbitrade/runtime/lifecycle.py

@@ -0,0 +1,224 @@
+from __future__ import annotations
+
+import inspect
+from dataclasses import dataclass
+from datetime import UTC, datetime
+from typing import Any, cast
+
+from fastapi import FastAPI
+
+from arbitrade.api.control_state import DashboardControlState
+from arbitrade.storage.db import DuckDBStore
+from arbitrade.storage.repositories import (
+    AuditRecord,
+    AuditRepository,
+    RuntimeStateRecord,
+    RuntimeStateRepository,
+)
+
+
+@dataclass(slots=True)
+class RuntimeRecoveryReport:
+    restored_from_snapshot: bool
+    snapshot_at: str | None
+    open_trades_detected: int
+    restart_guard_active: bool
+
+
+def _controls(app: FastAPI) -> DashboardControlState:
+    return cast(DashboardControlState, app.state.dashboard_controls)
+
+
+def _store(app: FastAPI) -> DuckDBStore:
+    return cast(DuckDBStore, app.state.store)
+
+
+def _audit_repository(app: FastAPI) -> AuditRepository | None:
+    repository = getattr(app.state, "audit_repository", None)
+    return repository if isinstance(repository, AuditRepository) else None
+
+
+def _runtime_repository(app: FastAPI) -> RuntimeStateRepository | None:
+    repository = getattr(app.state, "runtime_state_repository", None)
+    return repository if isinstance(repository, RuntimeStateRepository) else None
+
+
+def _open_trade_count(store: DuckDBStore) -> int:
+    with store.connect() as conn:
+        row = conn.execute("""
+            SELECT COUNT(*)
+            FROM trades
+            WHERE finished_at IS NULL
+            """).fetchone()
+    return int(row[0]) if row is not None else 0
+
+
+def _latest_balances(store: DuckDBStore) -> dict[str, Any] | None:
+    with store.connect() as conn:
+        row = conn.execute("""
+            SELECT balances
+            FROM portfolio_snapshots
+            ORDER BY snapshot_at DESC
+            LIMIT 1
+            """).fetchone()
+
+    if row is None or row[0] is None:
+        return None
+    raw_balances = row[0]
+    if isinstance(raw_balances, str):
+        return {"raw": raw_balances}
+    return {"raw": str(raw_balances)}
+
+
+def _record_audit(
+    app: FastAPI,
+    *,
+    event_type: str,
+    decision: str,
+    payload: dict[str, Any] | None = None,
+) -> None:
+    repository = _audit_repository(app)
+    if repository is None:
+        return
+    repository.insert(
+        AuditRecord(
+            occurred_at=datetime.now(UTC),
+            actor="runtime",
+            event_type=event_type,
+            decision=decision,
+            payload=payload,
+            correlation_id=None,
+        )
+    )
+
+
+async def _run_startup_reconciler(app: FastAPI) -> None:
+    reconciler = getattr(app.state, "startup_reconciler", None)
+    if reconciler is None:
+        return
+
+    reconcile_member = getattr(reconciler, "reconcile_open_trades", None)
+    if reconcile_member is None or not callable(reconcile_member):
+        return
+
+    result = reconcile_member()
+    if inspect.isawaitable(result):
+        await result
+
+
+def persist_runtime_snapshot(app: FastAPI, *, note: str | None = None) -> RuntimeStateRecord | None:
+    repository = _runtime_repository(app)
+    if repository is None:
+        return None
+
+    controls = _controls(app)
+    store = _store(app)
+    snapshot = RuntimeStateRecord(
+        snapshot_at=datetime.now(UTC),
+        is_running=controls.is_running,
+        kill_switch_active=controls.kill_switch.is_active,
+        kill_switch_reason=controls.kill_switch.reason,
+        open_trade_count=_open_trade_count(store),
+        last_known_balances=_latest_balances(store),
+        note=note,
+    )
+    repository.insert(snapshot)
+    return snapshot
+
+
+async def restore_runtime_state(app: FastAPI) -> RuntimeRecoveryReport:
+    controls = _controls(app)
+    store = _store(app)
+    runtime_repository = _runtime_repository(app)
+
+    restored_from_snapshot = False
+    snapshot_at: str | None = None
+
+    latest = runtime_repository.latest() if runtime_repository is not None else None
+    if latest is not None:
+        restored_from_snapshot = True
+        snapshot_at = latest.snapshot_at.isoformat()
+        controls.is_running = latest.is_running
+        if latest.kill_switch_active:
+            controls.kill_switch.activate(
+                reason=latest.kill_switch_reason or "recovered")
+        else:
+            controls.kill_switch.deactivate()
+        controls.mark_updated()
+
+    open_trades = _open_trade_count(store)
+    restart_guard_active = False
+    if open_trades > 0:
+        controls.is_running = False
+        if not controls.kill_switch.is_active:
+            controls.kill_switch.activate(
+                reason="recovery_open_trades_detected")
+        controls.mark_updated()
+        restart_guard_active = True
+
+    report = RuntimeRecoveryReport(
+        restored_from_snapshot=restored_from_snapshot,
+        snapshot_at=snapshot_at,
+        open_trades_detected=open_trades,
+        restart_guard_active=restart_guard_active,
+    )
+    app.state.recovery_report = report
+
+    _record_audit(
+        app,
+        event_type="runtime.startup_recovery",
+        decision="applied",
+        payload={
+            "restored_from_snapshot": restored_from_snapshot,
+            "open_trades_detected": open_trades,
+            "restart_guard_active": restart_guard_active,
+        },
+    )
+
+    await _run_startup_reconciler(app)
+
+    return report
+
+
+async def drain_background_workers(app: FastAPI) -> None:
+    workers: list[object] = []
+
+    declared = getattr(app.state, "background_workers", None)
+    if isinstance(declared, list):
+        workers.extend(declared)
+
+    for attr_name in ("execution_writer", "opportunity_writer", "snapshot_writer"):
+        worker = getattr(app.state, attr_name, None)
+        if worker is not None:
+            workers.append(worker)
+
+    seen: set[int] = set()
+    for worker in workers:
+        worker_id = id(worker)
+        if worker_id in seen:
+            continue
+        seen.add(worker_id)
+
+        stop_member = getattr(worker, "stop", None)
+        if stop_member is None or not callable(stop_member):
+            continue
+
+        result = stop_member()
+        if inspect.isawaitable(result):
+            await result
+
+
+async def graceful_shutdown(app: FastAPI) -> None:
+    controls = _controls(app)
+    controls.is_running = False
+    controls.mark_updated()
+
+    _record_audit(
+        app,
+        event_type="runtime.shutdown",
+        decision="initiated",
+        payload={"execution_status": "stopped"},
+    )
+
+    await drain_background_workers(app)
+    persist_runtime_snapshot(app, note="graceful_shutdown")

src/arbitrade/storage/__init__.py

@@ -0,0 +1 @@
+"""Storage helpers."""

src/arbitrade/storage/db.py

@@ -5,9 +5,12 @@ from contextlib import contextmanager
 from pathlib import Path
 
 import duckdb
+import structlog
 
 from arbitrade.config.settings import Settings
 
+_LOG = structlog.get_logger(__name__)
+
 SCHEMA_SQL = """
 CREATE TABLE IF NOT EXISTS schema_migrations (
     version INTEGER PRIMARY KEY,
@@ -26,11 +29,40 @@ CREATE TABLE IF NOT EXISTS opportunities (
 
 CREATE TABLE IF NOT EXISTS trades (
     id UUID DEFAULT uuid(),
+    trade_ref VARCHAR NOT NULL,
     started_at TIMESTAMP NOT NULL,
     finished_at TIMESTAMP,
     status VARCHAR NOT NULL,
     realized_pnl DOUBLE,
-    capital_used DOUBLE
+    estimated_pnl DOUBLE,
+    capital_used DOUBLE,
+    cycle VARCHAR,
+    leg_count INTEGER
+);
+
+CREATE TABLE IF NOT EXISTS orders (
+    id UUID DEFAULT uuid(),
+    trade_ref VARCHAR NOT NULL,
+    order_ref VARCHAR NOT NULL,
+    leg_index INTEGER NOT NULL,
+    pair VARCHAR NOT NULL,
+    side VARCHAR NOT NULL,
+    volume DOUBLE NOT NULL,
+    user_ref INTEGER,
+    status VARCHAR,
+    filled_volume DOUBLE,
+    avg_price DOUBLE,
+    raw_response JSON,
+    recorded_at TIMESTAMP NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS pnl_events (
+    id UUID DEFAULT uuid(),
+    trade_ref VARCHAR NOT NULL,
+    recorded_at TIMESTAMP NOT NULL,
+    kind VARCHAR NOT NULL,
+    pnl_usd DOUBLE NOT NULL,
+    source VARCHAR NOT NULL
 );
 
 CREATE TABLE IF NOT EXISTS portfolio_snapshots (
@@ -38,6 +70,34 @@ CREATE TABLE IF NOT EXISTS portfolio_snapshots (
     balances JSON,
     total_value_usd DOUBLE
 );
+
+CREATE TABLE IF NOT EXISTS market_snapshots (
+    snapshot_at TIMESTAMP NOT NULL,
+    symbol VARCHAR NOT NULL,
+    source VARCHAR NOT NULL,
+    payload JSON NOT NULL,
+    latency_ms DOUBLE
+);
+
+CREATE TABLE IF NOT EXISTS audit_events (
+    id UUID DEFAULT uuid(),
+    occurred_at TIMESTAMP NOT NULL,
+    actor VARCHAR NOT NULL,
+    event_type VARCHAR NOT NULL,
+    decision VARCHAR NOT NULL,
+    payload JSON,
+    correlation_id VARCHAR
+);
+
+CREATE TABLE IF NOT EXISTS runtime_state_snapshots (
+    snapshot_at TIMESTAMP NOT NULL,
+    is_running BOOLEAN NOT NULL,
+    kill_switch_active BOOLEAN NOT NULL,
+    kill_switch_reason VARCHAR,
+    open_trade_count INTEGER NOT NULL,
+    last_known_balances JSON,
+    note VARCHAR
+);
 """
 
 
@@ -45,10 +105,19 @@ class DuckDBStore:
     def __init__(self, settings: Settings) -> None:
         self._db_path = Path(settings.duckdb_path)
         self._db_path.parent.mkdir(parents=True, exist_ok=True)
+        self._use_memory_fallback = False
 
     @contextmanager
     def connect(self) -> Iterator[duckdb.DuckDBPyConnection]:
+        try:
             conn = duckdb.connect(str(self._db_path))
+        except duckdb.IOException:
+            if not self._use_memory_fallback:
+                _LOG.warning(
+                    "duckdb_path_unavailable_falling_back_to_memory", path=str(self._db_path)
+                )
+                self._use_memory_fallback = True
+            conn = duckdb.connect(":memory:")
         try:
             yield conn
         finally:

src/arbitrade/storage/executions.py

@@ -0,0 +1,66 @@
+from __future__ import annotations
+
+import asyncio
+
+import structlog
+
+from arbitrade.storage.repositories import (
+    OrderRecord,
+    OrderRepository,
+    PnLRecord,
+    PnLRepository,
+    TradeRecord,
+    TradeRepository,
+)
+
+_LOG = structlog.get_logger(__name__)
+
+
+class AsyncExecutionWriter:
+    def __init__(
+        self,
+        trade_repository: TradeRepository,
+        order_repository: OrderRepository,
+        pnl_repository: PnLRepository,
+        max_queue_size: int = 50_000,
+    ) -> None:
+        self._trade_repository = trade_repository
+        self._order_repository = order_repository
+        self._pnl_repository = pnl_repository
+        self._queue: asyncio.Queue[TradeRecord | OrderRecord | PnLRecord] = asyncio.Queue(
+            maxsize=max_queue_size
+        )
+        self._task: asyncio.Task[None] | None = None
+        self._stop = asyncio.Event()
+
+    async def start(self) -> None:
+        if self._task is None or self._task.done():
+            self._stop.clear()
+            self._task = asyncio.create_task(self._run(), name="execution-writer")
+
+    async def stop(self) -> None:
+        self._stop.set()
+        if self._task is not None:
+            await self._task
+
+    async def enqueue(self, record: TradeRecord | OrderRecord | PnLRecord) -> None:
+        await self._queue.put(record)
+
+    async def _run(self) -> None:
+        while not (self._stop.is_set() and self._queue.empty()):
+            try:
+                record = await asyncio.wait_for(self._queue.get(), timeout=0.5)
+            except TimeoutError:
+                continue
+
+            try:
+                if isinstance(record, TradeRecord):
+                    self._trade_repository.insert(record)
+                elif isinstance(record, OrderRecord):
+                    self._order_repository.insert(record)
+                else:
+                    self._pnl_repository.insert(record)
+            except Exception as exc:
+                _LOG.error("execution_write_failed", error=str(exc))
+            finally:
+                self._queue.task_done()

src/arbitrade/storage/market_snapshots.py

@@ -0,0 +1,64 @@
+from __future__ import annotations
+
+import asyncio
+from dataclasses import dataclass
+from datetime import datetime
+from typing import Any
+
+import structlog
+
+from arbitrade.storage.repositories import MarketSnapshotRecord, MarketSnapshotRepository
+
+_LOG = structlog.get_logger(__name__)
+
+
+@dataclass(slots=True)
+class MarketSnapshot:
+    snapshot_at: datetime
+    symbol: str
+    source: str
+    payload: dict[str, Any]
+    latency_ms: float | None
+
+
+class AsyncMarketSnapshotWriter:
+    def __init__(self, repository: MarketSnapshotRepository, max_queue_size: int = 50_000) -> None:
+        self._repository = repository
+        self._queue: asyncio.Queue[MarketSnapshot] = asyncio.Queue(maxsize=max_queue_size)
+        self._task: asyncio.Task[None] | None = None
+        self._stop = asyncio.Event()
+
+    async def start(self) -> None:
+        if self._task is None or self._task.done():
+            self._stop.clear()
+            self._task = asyncio.create_task(self._run(), name="market-snapshot-writer")
+
+    async def stop(self) -> None:
+        self._stop.set()
+        if self._task is not None:
+            await self._task
+
+    async def enqueue(self, snapshot: MarketSnapshot) -> None:
+        await self._queue.put(snapshot)
+
+    async def _run(self) -> None:
+        while not (self._stop.is_set() and self._queue.empty()):
+            try:
+                item = await asyncio.wait_for(self._queue.get(), timeout=0.5)
+            except TimeoutError:
+                continue
+
+            try:
+                self._repository.insert(
+                    MarketSnapshotRecord(
+                        snapshot_at=item.snapshot_at,
+                        symbol=item.symbol,
+                        source=item.source,
+                        payload=item.payload,
+                        latency_ms=item.latency_ms,
+                    )
+                )
+            except Exception as exc:
+                _LOG.error("market_snapshot_write_failed", error=str(exc), symbol=item.symbol)
+            finally:
+                self._queue.task_done()

src/arbitrade/storage/opportunities.py

@@ -0,0 +1,58 @@
+from __future__ import annotations
+
+import asyncio
+
+import structlog
+
+from arbitrade.detection.engine import OpportunityEvent
+from arbitrade.storage.repositories import OpportunityRecord, OpportunityRepository
+
+_LOG = structlog.get_logger(__name__)
+
+
+class AsyncOpportunityWriter:
+    def __init__(self, repository: OpportunityRepository, max_queue_size: int = 50_000) -> None:
+        self._repository = repository
+        self._queue: asyncio.Queue[OpportunityEvent] = asyncio.Queue(maxsize=max_queue_size)
+        self._task: asyncio.Task[None] | None = None
+        self._stop = asyncio.Event()
+
+    async def start(self) -> None:
+        if self._task is None or self._task.done():
+            self._stop.clear()
+            self._task = asyncio.create_task(self._run(), name="opportunity-writer")
+
+    async def stop(self) -> None:
+        self._stop.set()
+        if self._task is not None:
+            await self._task
+
+    async def enqueue(self, event: OpportunityEvent) -> None:
+        await self._queue.put(event)
+
+    async def _run(self) -> None:
+        while not (self._stop.is_set() and self._queue.empty()):
+            try:
+                event = await asyncio.wait_for(self._queue.get(), timeout=0.5)
+            except TimeoutError:
+                continue
+
+            try:
+                self._repository.insert(
+                    OpportunityRecord(
+                        detected_at=event.detected_at,
+                        cycle=event.cycle,
+                        gross_pct=event.gross_pct,
+                        net_pct=event.net_pct,
+                        est_profit=event.est_profit,
+                    )
+                )
+            except Exception as exc:
+                _LOG.error(
+                    "opportunity_write_failed",
+                    error=str(exc),
+                    cycle=event.cycle,
+                    updated_pair=event.updated_pair,
+                )
+            finally:
+                self._queue.task_done()

src/arbitrade/storage/repositories.py

@@ -0,0 +1,378 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import datetime
+from typing import Any
+
+import orjson
+
+from arbitrade.storage.db import DuckDBStore
+
+
+@dataclass(slots=True)
+class MarketSnapshotRecord:
+    snapshot_at: datetime
+    symbol: str
+    source: str
+    payload: dict[str, Any]
+    latency_ms: float | None
+
+
+@dataclass(slots=True)
+class OpportunityRecord:
+    detected_at: datetime
+    cycle: str
+    gross_pct: float
+    net_pct: float
+    est_profit: float
+    executed: bool = False
+
+
+@dataclass(slots=True)
+class TradeRecord:
+    trade_ref: str
+    started_at: datetime
+    finished_at: datetime | None
+    status: str
+    realized_pnl: float | None
+    estimated_pnl: float | None
+    capital_used: float | None
+    cycle: str | None = None
+    leg_count: int | None = None
+
+
+@dataclass(slots=True)
+class OrderRecord:
+    trade_ref: str
+    order_ref: str
+    leg_index: int
+    pair: str
+    side: str
+    volume: float
+    user_ref: int | None
+    status: str | None
+    filled_volume: float | None
+    avg_price: float | None
+    raw_response: dict[str, Any]
+    recorded_at: datetime
+
+
+@dataclass(slots=True)
+class PnLRecord:
+    trade_ref: str
+    recorded_at: datetime
+    kind: str
+    pnl_usd: float
+    source: str
+
+
+@dataclass(slots=True)
+class AuditRecord:
+    occurred_at: datetime
+    actor: str
+    event_type: str
+    decision: str
+    payload: dict[str, Any] | None = None
+    correlation_id: str | None = None
+
+
+@dataclass(slots=True)
+class RuntimeStateRecord:
+    snapshot_at: datetime
+    is_running: bool
+    kill_switch_active: bool
+    kill_switch_reason: str | None
+    open_trade_count: int
+    last_known_balances: dict[str, Any] | None = None
+    note: str | None = None
+
+
+class MarketSnapshotRepository:
+    def __init__(self, store: DuckDBStore) -> None:
+        self._store = store
+
+    def insert(self, record: MarketSnapshotRecord) -> None:
+        with self._store.connect() as conn:
+            conn.execute(
+                """
+                INSERT INTO market_snapshots (snapshot_at, symbol, source, payload, latency_ms)
+                VALUES (?, ?, ?, ?, ?)
+                """,
+                [
+                    record.snapshot_at,
+                    record.symbol,
+                    record.source,
+                    orjson.dumps(record.payload).decode("utf-8"),
+                    record.latency_ms,
+                ],
+            )
+
+
+class OpportunityRepository:
+    def __init__(self, store: DuckDBStore) -> None:
+        self._store = store
+
+    def insert(self, record: OpportunityRecord) -> None:
+        with self._store.connect() as conn:
+            conn.execute(
+                """
+                INSERT INTO opportunities (
+                    detected_at,
+                    cycle,
+                    gross_pct,
+                    net_pct,
+                    est_profit,
+                    executed
+                )
+                VALUES (?, ?, ?, ?, ?, ?)
+                """,
+                [
+                    record.detected_at,
+                    record.cycle,
+                    record.gross_pct,
+                    record.net_pct,
+                    record.est_profit,
+                    record.executed,
+                ],
+            )
+
+
+class TradeRepository:
+    def __init__(self, store: DuckDBStore) -> None:
+        self._store = store
+
+    def insert(self, record: TradeRecord) -> None:
+        with self._store.connect() as conn:
+            conn.execute(
+                """
+                INSERT INTO trades (
+                    trade_ref,
+                    started_at,
+                    finished_at,
+                    status,
+                    realized_pnl,
+                    estimated_pnl,
+                    capital_used,
+                    cycle,
+                    leg_count
+                )
+                VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+                """,
+                [
+                    record.trade_ref,
+                    record.started_at,
+                    record.finished_at,
+                    record.status,
+                    record.realized_pnl,
+                    record.estimated_pnl,
+                    record.capital_used,
+                    record.cycle,
+                    record.leg_count,
+                ],
+            )
+
+
+class OrderRepository:
+    def __init__(self, store: DuckDBStore) -> None:
+        self._store = store
+
+    def insert(self, record: OrderRecord) -> None:
+        with self._store.connect() as conn:
+            conn.execute(
+                """
+                INSERT INTO orders (
+                    trade_ref,
+                    order_ref,
+                    leg_index,
+                    pair,
+                    side,
+                    volume,
+                    user_ref,
+                    status,
+                    filled_volume,
+                    avg_price,
+                    raw_response,
+                    recorded_at
+                )
+                VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+                """,
+                [
+                    record.trade_ref,
+                    record.order_ref,
+                    record.leg_index,
+                    record.pair,
+                    record.side,
+                    record.volume,
+                    record.user_ref,
+                    record.status,
+                    record.filled_volume,
+                    record.avg_price,
+                    orjson.dumps(record.raw_response).decode("utf-8"),
+                    record.recorded_at,
+                ],
+            )
+
+
+class PnLRepository:
+    def __init__(self, store: DuckDBStore) -> None:
+        self._store = store
+
+    def insert(self, record: PnLRecord) -> None:
+        with self._store.connect() as conn:
+            conn.execute(
+                """
+                INSERT INTO pnl_events (
+                    trade_ref,
+                    recorded_at,
+                    kind,
+                    pnl_usd,
+                    source
+                )
+                VALUES (?, ?, ?, ?, ?)
+                """,
+                [
+                    record.trade_ref,
+                    record.recorded_at,
+                    record.kind,
+                    record.pnl_usd,
+                    record.source,
+                ],
+            )
+
+
+class AuditRepository:
+    def __init__(self, store: DuckDBStore) -> None:
+        self._store = store
+
+    def insert(self, record: AuditRecord) -> None:
+        with self._store.connect() as conn:
+            conn.execute(
+                """
+                INSERT INTO audit_events (
+                    occurred_at,
+                    actor,
+                    event_type,
+                    decision,
+                    payload,
+                    correlation_id
+                )
+                VALUES (?, ?, ?, ?, ?, ?)
+                """,
+                [
+                    record.occurred_at,
+                    record.actor,
+                    record.event_type,
+                    record.decision,
+                    (
+                        None
+                        if record.payload is None
+                        else orjson.dumps(record.payload).decode("utf-8")
+                    ),
+                    record.correlation_id,
+                ],
+            )
+
+    def list_recent(self, *, limit: int = 25) -> list[AuditRecord]:
+        with self._store.connect() as conn:
+            rows = conn.execute(
+                """
+                SELECT occurred_at, actor, event_type, decision, payload, correlation_id
+                FROM audit_events
+                ORDER BY occurred_at DESC
+                LIMIT ?
+                """,
+                [limit],
+            ).fetchall()
+
+        records: list[AuditRecord] = []
+        for row in rows:
+            payload: dict[str, Any] | None = None
+            raw_payload = row[4]
+            if isinstance(raw_payload, str) and raw_payload:
+                decoded = orjson.loads(raw_payload)
+                if isinstance(decoded, dict):
+                    payload = {str(k): decoded[k] for k in decoded}
+
+            records.append(
+                AuditRecord(
+                    occurred_at=row[0],
+                    actor=str(row[1]),
+                    event_type=str(row[2]),
+                    decision=str(row[3]),
+                    payload=payload,
+                    correlation_id=str(row[5]) if row[5] is not None else None,
+                )
+            )
+
+        return records
+
+
+class RuntimeStateRepository:
+    def __init__(self, store: DuckDBStore) -> None:
+        self._store = store
+
+    def insert(self, record: RuntimeStateRecord) -> None:
+        with self._store.connect() as conn:
+            conn.execute(
+                """
+                INSERT INTO runtime_state_snapshots (
+                    snapshot_at,
+                    is_running,
+                    kill_switch_active,
+                    kill_switch_reason,
+                    open_trade_count,
+                    last_known_balances,
+                    note
+                )
+                VALUES (?, ?, ?, ?, ?, ?, ?)
+                """,
+                [
+                    record.snapshot_at,
+                    record.is_running,
+                    record.kill_switch_active,
+                    record.kill_switch_reason,
+                    record.open_trade_count,
+                    (
+                        None
+                        if record.last_known_balances is None
+                        else orjson.dumps(record.last_known_balances).decode("utf-8")
+                    ),
+                    record.note,
+                ],
+            )
+
+    def latest(self) -> RuntimeStateRecord | None:
+        with self._store.connect() as conn:
+            row = conn.execute("""
+                SELECT
+                    snapshot_at,
+                    is_running,
+                    kill_switch_active,
+                    kill_switch_reason,
+                    open_trade_count,
+                    last_known_balances,
+                    note
+                FROM runtime_state_snapshots
+                ORDER BY snapshot_at DESC
+                LIMIT 1
+                """).fetchone()
+
+        if row is None:
+            return None
+
+        balances: dict[str, Any] | None = None
+        raw_balances = row[5]
+        if isinstance(raw_balances, str) and raw_balances:
+            decoded = orjson.loads(raw_balances)
+            if isinstance(decoded, dict):
+                balances = {str(key): decoded[key] for key in decoded}
+
+        return RuntimeStateRecord(
+            snapshot_at=row[0],
+            is_running=bool(row[1]),
+            kill_switch_active=bool(row[2]),
+            kill_switch_reason=str(row[3]) if row[3] is not None else None,
+            open_trade_count=int(row[4]),
+            last_known_balances=balances,
+            note=str(row[6]) if row[6] is not None else None,
+        )

tests/test_dashboard.py

@@ -0,0 +1,321 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime, timedelta
+from typing import Any
+
+import httpx
+
+from arbitrade.api.app import create_app
+from arbitrade.config.settings import Settings
+
+
+class _FakeAlertNotifier:
+    def __init__(self) -> None:
+        self.events: list[dict[str, Any]] = []
+
+    async def notify(
+        self,
+        *,
+        category: str,
+        severity: str,
+        title: str,
+        message: str,
+        details: dict[str, str] | None = None,
+    ) -> bool:
+        self.events.append(
+            {
+                "category": category,
+                "severity": severity,
+                "title": title,
+                "message": message,
+                "details": details or {},
+            }
+        )
+        return True
+
+
+def _seed_metrics_data(app) -> None:
+    store = app.state.store
+    started = datetime.now(UTC)
+    finished = started + timedelta(seconds=20)
+    with store.connect() as conn:
+        conn.execute(
+            """
+            INSERT INTO trades (
+                trade_ref,
+                started_at,
+                finished_at,
+                status,
+                realized_pnl,
+                estimated_pnl,
+                capital_used,
+                cycle,
+                leg_count
+            ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+            """,
+            [
+                "trade-1",
+                started,
+                finished,
+                "filled",
+                15.0,
+                10.0,
+                100.0,
+                "USD->BTC->ETH->USD",
+                3,
+            ],
+        )
+        conn.execute(
+            """
+            INSERT INTO opportunities (
+                detected_at,
+                cycle,
+                gross_pct,
+                net_pct,
+                est_profit,
+                executed
+            ) VALUES (?, ?, ?, ?, ?, ?)
+            """,
+            [started, "USD->BTC->ETH->USD", 4.0, 3.0, 0.03, True],
+        )
+        conn.execute(
+            """
+            INSERT INTO orders (
+                trade_ref,
+                order_ref,
+                leg_index,
+                pair,
+                side,
+                volume,
+                user_ref,
+                status,
+                filled_volume,
+                avg_price,
+                raw_response,
+                recorded_at
+            ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+            """,
+            [
+                "trade-1",
+                "order-1",
+                0,
+                "BTC/USD",
+                "buy",
+                2.0,
+                100,
+                "closed",
+                2.0,
+                100.0,
+                "{}",
+                started,
+            ],
+        )
+        conn.execute(
+            """
+            INSERT INTO portfolio_snapshots (
+                snapshot_at,
+                balances,
+                total_value_usd
+            ) VALUES (?, ?, ?)
+            """,
+            [started, '{"USD": 1000.0, "BTC": 0.25}', 1250.0],
+        )
+        conn.execute(
+            """
+            INSERT INTO trades (
+                trade_ref,
+                started_at,
+                finished_at,
+                status,
+                realized_pnl,
+                estimated_pnl,
+                capital_used,
+                cycle,
+                leg_count
+            ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+            """,
+            [
+                "trade-open",
+                started,
+                None,
+                "open",
+                None,
+                5.0,
+                50.0,
+                "USD->BTC->ETH->USD",
+                3,
+            ],
+        )
+
+
+async def test_dashboard_page_and_fragment_and_sse(tmp_path) -> None:
+    app = create_app(Settings(DUCKDB_PATH=tmp_path / "dash.duckdb"))
+    _seed_metrics_data(app)
+
+    transport = httpx.ASGITransport(app=app)
+    async with httpx.AsyncClient(transport=transport, base_url="http://test") as client:
+        page = await client.get("/")
+        fragment = await client.get("/dashboard/fragment/metrics")
+        stream = await client.get("/dashboard/stream/metrics")
+        overview = await client.get("/dashboard/fragment/overview")
+        overview_stream = await client.get("/dashboard/stream/overview")
+        controls = await client.get("/dashboard/fragment/controls")
+        charts = await client.get("/dashboard/fragment/charts")
+        audit = await client.get("/dashboard/fragment/audit")
+
+    assert page.status_code == 200
+    assert "EventSource" in page.text
+    assert "alpinejs" in page.text.lower()
+    assert "Chart.js" in page.text or "chart.umd.min.js" in page.text
+    assert 'hx-get="/dashboard/fragment/metrics"' in page.text
+    assert 'hx-get="/dashboard/fragment/controls"' in page.text
+    assert 'hx-get="/dashboard/fragment/charts"' in page.text
+    assert 'hx-get="/dashboard/fragment/audit"' in page.text
+
+    assert fragment.status_code == 200
+    assert "Realized P&L" in fragment.text
+    assert "15.00 USD" in fragment.text
+    assert "100.0%" in fragment.text
+
+    assert stream.status_code == 200
+    assert stream.headers["content-type"].startswith("text/event-stream")
+    assert "event: metrics" in stream.text
+    assert "Realized P&L" in stream.text
+
+    assert overview.status_code == 200
+    assert "live" in overview.text
+    assert "Balances Snapshot" in overview.text
+    assert "Open Trades" in overview.text
+    assert "Opportunity Feed" in overview.text
+    assert "1250.00 USD" in overview.text
+    assert "trade-open" in overview.text
+
+    assert overview_stream.status_code == 200
+    assert overview_stream.headers["content-type"].startswith("text/event-stream")
+    assert "event: overview" in overview_stream.text
+    assert "trade-open" in overview_stream.text
+
+    assert controls.status_code == 200
+    assert "Runtime Status" in controls.text
+    assert ">running<" in controls.text
+    assert "Alerting" in controls.text
+    assert "Last result" in controls.text
+    assert "Paper trading mode" in controls.text
+    assert "Trade capital USD" in controls.text
+
+    assert charts.status_code == 200
+    assert "Opportunity Trend" in charts.text
+    assert "opportunity-chart" in charts.text
+    assert "Hide chart" in charts.text or "Show chart" in charts.text
+
+    assert audit.status_code == 200
+    assert "Audit Trail" in audit.text
+
+
+async def test_dashboard_controls_update_runtime_state_and_config(tmp_path) -> None:
+    app = create_app(Settings(DUCKDB_PATH=tmp_path / "controls.duckdb"))
+
+    transport = httpx.ASGITransport(app=app)
+    async with httpx.AsyncClient(transport=transport, base_url="http://test") as client:
+        stop_response = await client.post("/dashboard/control/stop")
+        start_response = await client.post("/dashboard/control/start")
+        kill_response = await client.post(
+            "/dashboard/control/kill-switch",
+            data={"reason": "manual"},
+        )
+        config_response = await client.post(
+            "/dashboard/control/config",
+            data={
+                "trade_capital_usd": "250.50",
+                "max_trade_capital_usd": "300.00",
+                "max_concurrent_trades": "4",
+                "paper_trading_mode": "on",
+            },
+        )
+
+    assert stop_response.status_code == 200
+    assert ">stopped<" in stop_response.text
+
+    assert start_response.status_code == 200
+    assert ">running<" in start_response.text
+
+    assert kill_response.status_code == 200
+    assert ">active<" in kill_response.text
+    assert "manual" in kill_response.text
+
+    assert config_response.status_code == 200
+    assert "250.50 USD" in config_response.text
+    assert "300.00 USD" in config_response.text
+    assert "4" in config_response.text
+    assert app.state.settings.trade_capital_usd == 250.5
+    assert app.state.settings.max_trade_capital_usd == 300.0
+    assert app.state.settings.max_concurrent_trades == 4
+    assert app.state.settings.paper_trading_mode is True
+
+    transport = httpx.ASGITransport(app=app)
+    async with httpx.AsyncClient(transport=transport, base_url="http://test") as client:
+        audit_recent = await client.get("/dashboard/api/audit/recent")
+
+    assert audit_recent.status_code == 200
+    entries = audit_recent.json()["entries"]
+    assert len(entries) >= 4
+    assert any(entry["event_type"] == "dashboard.control.stop" for entry in entries)
+    assert any(entry["event_type"] == "dashboard.control.start" for entry in entries)
+    assert any(entry["event_type"] == "dashboard.control.kill_switch" for entry in entries)
+    assert any(entry["event_type"] == "dashboard.control.config" for entry in entries)
+
+
+async def test_dashboard_controls_emit_alerts(tmp_path) -> None:
+    app = create_app(Settings(DUCKDB_PATH=tmp_path / "alerts.duckdb"))
+    fake_notifier = _FakeAlertNotifier()
+    app.state.alert_notifier = fake_notifier
+
+    transport = httpx.ASGITransport(app=app)
+    async with httpx.AsyncClient(transport=transport, base_url="http://test") as client:
+        await client.post("/dashboard/control/start")
+        await client.post("/dashboard/control/stop")
+        await client.post("/dashboard/control/kill-switch", data={"reason": "manual-test"})
+
+    assert len(fake_notifier.events) == 3
+    assert fake_notifier.events[0]["title"] == "Execution started"
+    assert fake_notifier.events[1]["title"] == "Execution stopped"
+    assert fake_notifier.events[2]["title"] == "Kill switch activated"
+    assert fake_notifier.events[2]["details"]["reason"] == "manual-test"
+
+
+async def test_dashboard_requires_basic_auth_when_configured(tmp_path) -> None:
+    app = create_app(
+        Settings(
+            DUCKDB_PATH=tmp_path / "auth.duckdb",
+            DASHBOARD_AUTH_USERNAME="admin",
+            DASHBOARD_AUTH_PASSWORD="secret",
+        )
+    )
+
+    transport = httpx.ASGITransport(app=app)
+    async with httpx.AsyncClient(transport=transport, base_url="http://test") as client:
+        unauthenticated = await client.get("/dashboard/fragment/overview")
+        authenticated = await client.get(
+            "/dashboard/fragment/overview",
+            auth=("admin", "secret"),
+        )
+        health = await client.get("/health")
+
+    assert unauthenticated.status_code == 401
+    assert unauthenticated.headers["www-authenticate"] == 'Basic realm="Arbitrade Dashboard"'
+    assert authenticated.status_code == 200
+    assert health.status_code == 200
+
+
+async def test_dashboard_alert_status_api_exposes_notifier_snapshot(tmp_path) -> None:
+    app = create_app(Settings(DUCKDB_PATH=tmp_path / "alerts-status.duckdb"))
+
+    transport = httpx.ASGITransport(app=app)
+    async with httpx.AsyncClient(transport=transport, base_url="http://test") as client:
+        response = await client.get("/dashboard/api/alerts/status")
+
+    assert response.status_code == 200
+    payload = response.json()
+    assert payload["enabled"] is True
+    assert "configured_channels" in payload
+    assert "last_result" in payload

tests/unit/test_alert_notifier.py

@@ -0,0 +1,131 @@
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+
+import pytest
+
+from arbitrade.alerting.notifier import AlertEvent, AlertNotifier
+
+
+@dataclass(slots=True)
+class _FakeChannel:
+    events: list[AlertEvent] = field(default_factory=list)
+    fail: bool = False
+
+    async def send(self, event: AlertEvent) -> None:
+        if self.fail:
+            raise RuntimeError("channel send failed")
+        self.events.append(event)
+
+
+@pytest.mark.asyncio
+async def test_alert_notifier_sends_event_when_enabled() -> None:
+    channel = _FakeChannel()
+    notifier = AlertNotifier([channel], enabled=True, min_severity="info")
+
+    sent = await notifier.notify(
+        category="trade",
+        severity="info",
+        title="Trade complete",
+        message="Completed all legs.",
+    )
+
+    assert sent is True
+    assert len(channel.events) == 1
+    assert channel.events[0].category == "trade"
+
+
+@pytest.mark.asyncio
+async def test_alert_notifier_respects_severity_and_category_filters() -> None:
+    channel = _FakeChannel()
+    notifier = AlertNotifier(
+        [channel],
+        enabled=True,
+        min_severity="error",
+        category_flags={"trade": False, "error": True},
+    )
+
+    low = await notifier.notify(
+        category="error",
+        severity="warning",
+        title="Low",
+        message="Ignored by severity.",
+    )
+    filtered = await notifier.notify(
+        category="trade",
+        severity="critical",
+        title="Trade",
+        message="Ignored by category.",
+    )
+    high = await notifier.notify(
+        category="error",
+        severity="critical",
+        title="High",
+        message="Delivered.",
+    )
+
+    assert low is False
+    assert filtered is False
+    assert high is True
+    assert len(channel.events) == 1
+    assert channel.events[0].title == "High"
+
+
+@pytest.mark.asyncio
+async def test_alert_notifier_applies_dedup_window() -> None:
+    channel = _FakeChannel()
+    notifier = AlertNotifier([channel], dedup_seconds=60.0)
+
+    first = await notifier.notify(
+        category="error",
+        severity="error",
+        title="Burst",
+        message="Same message",
+    )
+    second = await notifier.notify(
+        category="error",
+        severity="error",
+        title="Burst",
+        message="Same message",
+    )
+
+    assert first is True
+    assert second is False
+    assert len(channel.events) == 1
+
+
+@pytest.mark.asyncio
+async def test_alert_notifier_returns_false_when_all_channels_fail() -> None:
+    notifier = AlertNotifier([_FakeChannel(fail=True), _FakeChannel(fail=True)])
+
+    sent = await notifier.notify(
+        category="error",
+        severity="critical",
+        title="Failure",
+        message="Both channels fail.",
+    )
+
+    assert sent is False
+
+
+@pytest.mark.asyncio
+async def test_alert_notifier_exposes_status_snapshot_for_dashboard() -> None:
+    channel = _FakeChannel()
+    notifier = AlertNotifier([channel], enabled=True, min_severity="info", dedup_seconds=30.0)
+
+    await notifier.notify(
+        category="system",
+        severity="warning",
+        title="Reconnect",
+        message="Socket restored.",
+    )
+
+    status = notifier.status_snapshot()
+
+    assert status["enabled"] is True
+    assert status["has_channels"] is True
+    assert status["configured_channels"] == ["_FakeChannel"]
+    assert status["last_result"] == "success"
+    assert status["last_attempted_at"] is not None
+    assert status["last_success_at"] is not None
+    assert status["last_event"] is not None

tests/unit/test_audit_repository.py

@@ -0,0 +1,34 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime
+
+from arbitrade.config.settings import Settings
+from arbitrade.storage.db import DuckDBStore
+from arbitrade.storage.repositories import AuditRecord, AuditRepository
+
+
+def test_audit_repository_inserts_and_lists_recent(tmp_path) -> None:
+    settings = Settings(_env_file=None, DUCKDB_PATH=tmp_path / "audit.duckdb")
+    store = DuckDBStore(settings)
+    store.migrate()
+    repository = AuditRepository(store)
+
+    repository.insert(
+        AuditRecord(
+            occurred_at=datetime.now(UTC),
+            actor="dashboard_user",
+            event_type="dashboard.control.start",
+            decision="approved",
+            payload={"execution_status": "running"},
+            correlation_id="req-1",
+        )
+    )
+
+    recent = repository.list_recent(limit=5)
+
+    assert len(recent) == 1
+    assert recent[0].actor == "dashboard_user"
+    assert recent[0].event_type == "dashboard.control.start"
+    assert recent[0].decision == "approved"
+    assert recent[0].payload == {"execution_status": "running"}
+    assert recent[0].correlation_id == "req-1"

tests/unit/test_currency_graph.py

@@ -0,0 +1,48 @@
+from arbitrade.detection.graph import CurrencyGraph
+
+
+def test_currency_graph_from_kraken_pairs_builds_adjacency() -> None:
+    asset_pairs = {
+        "XXBTZUSD": {"wsname": "BTC/USD"},
+        "XETHXXBT": {"wsname": "ETH/BTC"},
+        "XETHZUSD": {"wsname": "ETH/USD"},
+    }
+
+    graph = CurrencyGraph.from_kraken_asset_pairs(asset_pairs)
+
+    assert "USD" in graph.adjacency
+    assert "BTC" in graph.adjacency["USD"]
+    assert "ETH" in graph.adjacency["USD"]
+
+
+def test_triangular_cycles_detected_once() -> None:
+    asset_pairs = {
+        "XXBTZUSD": {"wsname": "BTC/USD"},
+        "XETHXXBT": {"wsname": "ETH/BTC"},
+        "XETHZUSD": {"wsname": "ETH/USD"},
+    }
+
+    graph = CurrencyGraph.from_kraken_asset_pairs(asset_pairs)
+    cycles = graph.triangular_cycles()
+
+    assert len(cycles) == 1
+    cycle = cycles[0]
+    assert cycle.currencies == ("BTC", "ETH", "USD")
+    assert set(cycle.pairs) == {"BTC/USD", "ETH/BTC", "ETH/USD"}
+
+
+def test_cycles_indexed_by_pair() -> None:
+    asset_pairs = {
+        "XXBTZUSD": {"wsname": "BTC/USD"},
+        "XETHXXBT": {"wsname": "ETH/BTC"},
+        "XETHZUSD": {"wsname": "ETH/USD"},
+    }
+
+    graph = CurrencyGraph.from_kraken_asset_pairs(asset_pairs)
+    cycles = graph.triangular_cycles()
+    index = graph.index_cycles_by_pair(cycles)
+
+    assert "BTC/USD" in index
+    assert "ETH/BTC" in index
+    assert "ETH/USD" in index
+    assert len(index["BTC/USD"]) == 1

tests/unit/test_detection_benchmark.py

@@ -0,0 +1,19 @@
+import pytest
+
+from arbitrade.detection.benchmark import run_incremental_detection_benchmark
+
+
+def test_incremental_detection_benchmark_returns_metrics() -> None:
+    result = run_incremental_detection_benchmark(iterations=500)
+
+    assert result.iterations == 500
+    assert result.total_ms > 0.0
+    assert result.avg_ms > 0.0
+    assert result.p50_ms > 0.0
+    assert result.p95_ms > 0.0
+    assert result.max_ms >= result.p95_ms
+
+
+def test_incremental_detection_benchmark_rejects_invalid_iterations() -> None:
+    with pytest.raises(ValueError, match="iterations"):
+        run_incremental_detection_benchmark(iterations=0)

tests/unit/test_detection_synthetic_books.py

@@ -0,0 +1,117 @@
+from __future__ import annotations
+
+import pytest
+
+from arbitrade.detection.engine import IncrementalCycleDetector
+from arbitrade.detection.graph import CurrencyGraph
+from arbitrade.exchange.models import BookLevel
+from arbitrade.market_data.order_book import OrderBook
+
+
+def _make_book(*, bid: float, ask: float) -> OrderBook:
+    book = OrderBook()
+    book.apply_bids([BookLevel(price=bid, volume=2_000.0)])
+    book.apply_asks([BookLevel(price=ask, volume=2_000.0)])
+    return book
+
+
+def _make_book_levels(
+    *, bids: list[tuple[float, float]], asks: list[tuple[float, float]]
+) -> OrderBook:
+    book = OrderBook()
+    book.apply_bids([BookLevel(price=price, volume=volume) for price, volume in bids])
+    book.apply_asks([BookLevel(price=price, volume=volume) for price, volume in asks])
+    return book
+
+
+def test_synthetic_single_cycle_known_exact_rates() -> None:
+    asset_pairs = {
+        "XXBTZUSD": {"wsname": "BTC/USD"},
+        "XETHXXBT": {"wsname": "ETH/BTC"},
+        "XETHZUSD": {"wsname": "ETH/USD"},
+    }
+    graph = CurrencyGraph.from_kraken_asset_pairs(asset_pairs)
+    detector = IncrementalCycleDetector(
+        graph.index_cycles_by_pair(graph.triangular_cycles()),
+        fee_rate=0.001,
+        max_depth_levels=1,
+    )
+
+    books = {
+        "BTC/USD": _make_book(bid=99.9, ask=100.0),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.20, ask=5.21),
+    }
+
+    scores = detector.score_updated_pair("ETH/BTC", books)
+
+    assert len(scores) == 1
+    score = scores[0]
+    # Known path result: 1 USD -> 0.01 BTC -> 0.2 ETH -> 1.04 USD gross.
+    assert score.gross_rate == pytest.approx(1.04)
+    assert score.net_rate == pytest.approx(1.04 * (1 - 0.001) ** 3)
+
+
+def test_synthetic_two_cycles_known_filtering_and_pair_index() -> None:
+    asset_pairs = {
+        "XXBTZUSD": {"wsname": "BTC/USD"},
+        "XETHXXBT": {"wsname": "ETH/BTC"},
+        "XETHZUSD": {"wsname": "ETH/USD"},
+        "XLTCXXBT": {"wsname": "LTC/BTC"},
+        "XLTCZUSD": {"wsname": "LTC/USD"},
+    }
+    graph = CurrencyGraph.from_kraken_asset_pairs(asset_pairs)
+    detector = IncrementalCycleDetector(
+        graph.index_cycles_by_pair(graph.triangular_cycles()),
+        min_profit_threshold=0.02,
+        max_depth_levels=3,
+    )
+
+    books = {
+        # ETH cycle expected to pass threshold (~4% gross)
+        "BTC/USD": _make_book(bid=99.9, ask=100.0),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.20, ask=5.21),
+        # LTC cycle expected to fail threshold (<2% gross)
+        "LTC/BTC": _make_book(bid=0.01005, ask=0.0101),
+        "LTC/USD": _make_book(bid=1.01, ask=1.011),
+    }
+
+    scores = detector.score_updated_pair("BTC/USD", books)
+
+    assert len(scores) == 1
+    assert scores[0].cycle.currencies == ("BTC", "ETH", "USD")
+    assert (scores[0].net_rate - 1.0) >= 0.02
+
+
+def test_synthetic_depth_scenario_known_no_result_when_not_fillable() -> None:
+    asset_pairs = {
+        "XXBTZUSD": {"wsname": "BTC/USD"},
+        "XETHXXBT": {"wsname": "ETH/BTC"},
+        "XETHZUSD": {"wsname": "ETH/USD"},
+    }
+    graph = CurrencyGraph.from_kraken_asset_pairs(asset_pairs)
+    detector = IncrementalCycleDetector(
+        graph.index_cycles_by_pair(graph.triangular_cycles()),
+        max_depth_levels=2,
+    )
+
+    books = {
+        # Not enough ask-side BTC/USD capacity inside top-2 levels for initial USD->BTC conversion.
+        "BTC/USD": _make_book_levels(
+            bids=[(99.9, 10.0)],
+            asks=[(100.0, 0.003), (101.0, 0.003)],
+        ),
+        "ETH/BTC": _make_book_levels(
+            bids=[(0.049, 10.0)],
+            asks=[(0.05, 10.0)],
+        ),
+        "ETH/USD": _make_book_levels(
+            bids=[(5.20, 10.0)],
+            asks=[(5.21, 10.0)],
+        ),
+    }
+
+    scores = detector.score_updated_pair("BTC/USD", books)
+
+    assert scores == []

tests/unit/test_execution_persistence.py

@@ -0,0 +1,89 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import UTC, datetime
+
+import pytest
+
+from arbitrade.config.settings import Settings
+from arbitrade.detection.engine import OpportunityEvent
+from arbitrade.execution.sequencer import TriangularExecutionSequencer
+from arbitrade.storage.db import DuckDBStore
+from arbitrade.storage.executions import AsyncExecutionWriter
+from arbitrade.storage.repositories import OrderRepository, PnLRepository, TradeRepository
+
+
+@dataclass(slots=True)
+class _FakeRestClient:
+    calls: int = 0
+
+    async def place_market_order(self, *, pair: str, side: str, volume: float) -> dict[str, object]:
+        self.calls += 1
+        return {"txid": [f"tx-{self.calls}"], "status": "submitted"}
+
+
+def _sample_event() -> OpportunityEvent:
+    return OpportunityEvent(
+        detected_at=datetime.now(UTC),
+        cycle="USD->BTC->ETH->USD",
+        updated_pair="BTC/USD",
+        gross_rate=1.04,
+        net_rate=1.03,
+        gross_pct=4.0,
+        net_pct=3.0,
+        est_profit=0.03,
+    )
+
+
+@pytest.mark.asyncio
+async def test_execution_writer_persists_trade_order_and_pnl(tmp_path) -> None:
+    settings = Settings(_env_file=None, DUCKDB_PATH=tmp_path / "exec.duckdb")
+    store = DuckDBStore(settings)
+    store.migrate()
+    writer = AsyncExecutionWriter(
+        TradeRepository(store),
+        OrderRepository(store),
+        PnLRepository(store),
+        max_queue_size=10,
+    )
+    await writer.start()
+
+    client = _FakeRestClient()
+    sequencer = TriangularExecutionSequencer(
+        client,
+        available_pairs=["BTC/USD", "ETH/BTC", "ETH/USD"],
+        execution_writer=writer,
+    )
+
+    result = await sequencer.execute(_sample_event())
+    await writer.stop()
+
+    assert result.success
+    assert client.calls == 3
+
+    with store.connect() as conn:
+        trades = conn.execute(
+            "SELECT trade_ref, status, estimated_pnl, capital_used, cycle, leg_count FROM trades"
+        ).fetchall()
+        orders = conn.execute(
+            "SELECT trade_ref, order_ref, leg_index, pair, side, volume, status "
+            "FROM orders ORDER BY leg_index"
+        ).fetchall()
+        pnls = conn.execute("SELECT trade_ref, kind, pnl_usd, source FROM pnl_events").fetchall()
+
+    assert len(trades) == 1
+    assert trades[0][1] == "filled"
+    assert trades[0][2] == 0.03
+    assert trades[0][3] == 1.0
+    assert trades[0][4] == "USD->BTC->ETH->USD"
+    assert trades[0][5] == 3
+
+    assert len(orders) == 3
+    assert orders[0][2] == 0
+    assert orders[1][2] == 1
+    assert orders[2][2] == 2
+    assert orders[0][6] == "submitted"
+
+    assert len(pnls) == 1
+    assert pnls[0][1] == "estimated"
+    assert pnls[0][2] == 0.03

tests/unit/test_execution_sequencer.py

@@ -0,0 +1,128 @@
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from datetime import UTC, datetime
+from typing import Any
+
+import pytest
+
+from arbitrade.detection.engine import OpportunityEvent
+from arbitrade.execution.sequencer import TriangularExecutionSequencer
+
+
+@dataclass(slots=True)
+class _FakeAlertNotifier:
+    events: list[dict[str, str]] = field(default_factory=list)
+
+    async def notify(
+        self,
+        *,
+        category: str,
+        severity: str,
+        title: str,
+        message: str,
+        details: dict[str, str] | None = None,
+    ) -> bool:
+        self.events.append(
+            {
+                "category": category,
+                "severity": severity,
+                "title": title,
+                "message": message,
+                **(details or {}),
+            }
+        )
+        return True
+
+
+@dataclass(slots=True)
+class _FakeRestClient:
+    fail_at_call: int | None = None
+    calls: list[dict[str, Any]] = field(default_factory=list)
+
+    async def place_market_order(self, *, pair: str, side: str, volume: float) -> dict[str, Any]:
+        call_number = len(self.calls) + 1
+        if self.fail_at_call is not None and call_number == self.fail_at_call:
+            raise RuntimeError("simulated failure")
+
+        payload = {"pair": pair, "side": side, "volume": volume}
+        self.calls.append(payload)
+        return {"txid": [f"tx-{call_number}"]}
+
+
+def _sample_event(cycle: str = "USD->BTC->ETH->USD") -> OpportunityEvent:
+    return OpportunityEvent(
+        detected_at=datetime.now(UTC),
+        cycle=cycle,
+        updated_pair="BTC/USD",
+        gross_rate=1.02,
+        net_rate=1.01,
+        gross_pct=2.0,
+        net_pct=1.0,
+        est_profit=1.0,
+        allocated_capital=10.0,
+    )
+
+
+@pytest.mark.asyncio
+async def test_triangular_sequencer_executes_legs_in_order() -> None:
+    client = _FakeRestClient()
+    notifier = _FakeAlertNotifier()
+    sequencer = TriangularExecutionSequencer(
+        client,
+        available_pairs=["BTC/USD", "ETH/BTC", "ETH/USD"],
+        alert_notifier=notifier,
+    )
+
+    result = await sequencer.execute(_sample_event())
+
+    assert result.success
+    assert result.completed_legs == 3
+    assert [call["pair"] for call in client.calls] == ["BTC/USD", "ETH/BTC", "ETH/USD"]
+    assert [call["side"] for call in client.calls] == ["buy", "buy", "sell"]
+    assert len(notifier.events) == 1
+    assert notifier.events[0]["category"] == "trade"
+    assert notifier.events[0]["title"] == "Trade execution completed"
+
+
+@pytest.mark.asyncio
+async def test_triangular_sequencer_stops_on_failed_leg() -> None:
+    client = _FakeRestClient(fail_at_call=2)
+    notifier = _FakeAlertNotifier()
+    sequencer = TriangularExecutionSequencer(
+        client,
+        available_pairs=["BTC/USD", "ETH/BTC", "ETH/USD"],
+        alert_notifier=notifier,
+    )
+
+    result = await sequencer.execute(_sample_event())
+
+    assert not result.success
+    assert result.completed_legs == 1
+    assert result.failure_reason is not None
+    assert len(client.calls) == 1
+    assert len(notifier.events) == 1
+    assert notifier.events[0]["category"] == "error"
+    assert notifier.events[0]["title"] == "Trade execution failed"
+
+
+def test_triangular_sequencer_rejects_non_closed_cycle() -> None:
+    client = _FakeRestClient()
+    sequencer = TriangularExecutionSequencer(
+        client,
+        available_pairs=["BTC/USD", "ETH/BTC", "ETH/USD"],
+    )
+
+    with pytest.raises(ValueError, match="closed triangular path"):
+        sequencer._build_legs(_sample_event(cycle="USD->BTC->ETH"))
+
+
+def test_triangular_sequencer_rejects_missing_pair() -> None:
+    client = _FakeRestClient()
+    sequencer = TriangularExecutionSequencer(
+        client,
+        available_pairs=["BTC/USD", "ETH/BTC"],
+    )
+
+    with pytest.raises(ValueError, match="No tradable pair"):
+        sequencer._build_legs(_sample_event())

tests/unit/test_fill_monitor.py

@@ -0,0 +1,112 @@
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from datetime import UTC, datetime
+from typing import Any
+
+import pytest
+
+from arbitrade.execution.fill_monitor import FillMonitor, OrderFillState
+
+
+@dataclass(slots=True)
+class _FakePollClient:
+    responses: list[dict[str, Any]]
+    calls: int = 0
+
+    async def query_order(self, *, order_id: str, include_trades: bool = True) -> dict[str, Any]:
+        self.calls += 1
+        if self.responses:
+            return self.responses.pop(0)
+        return {order_id: {"status": "open", "vol_exec": "0.0", "price": "0.0"}}
+
+
+@dataclass(slots=True)
+class _FakeWsProvider:
+    states: list[OrderFillState] = field(default_factory=list)
+
+    def get(self, _order_id: str) -> OrderFillState | None:
+        if not self.states:
+            return None
+        return self.states.pop(0)
+
+
+@pytest.mark.asyncio
+async def test_fill_monitor_detects_terminal_state_via_polling() -> None:
+    order_id = "order-1"
+    client = _FakePollClient(
+        responses=[
+            {order_id: {"status": "open", "vol_exec": "0.0", "price": "0.0"}},
+            {order_id: {"status": "closed", "vol_exec": "1.0", "price": "100.0"}},
+        ]
+    )
+    monitor = FillMonitor(client, poll_interval_seconds=0.001, max_wait_seconds=0.1)
+
+    result = await monitor.wait_for_terminal_fill(order_id)
+
+    assert not result.timed_out
+    assert result.terminal_state is not None
+    assert result.terminal_state.status == "closed"
+    assert result.terminal_state.filled_volume == 1.0
+    assert result.terminal_state.source == "rest_poll"
+
+
+@pytest.mark.asyncio
+async def test_fill_monitor_times_out_when_no_terminal_state() -> None:
+    order_id = "order-2"
+    client = _FakePollClient(
+        responses=[
+            {order_id: {"status": "open", "vol_exec": "0.1", "price": "100.0"}},
+            {order_id: {"status": "partial", "vol_exec": "0.2", "price": "100.0"}},
+            {order_id: {"status": "open", "vol_exec": "0.2", "price": "100.0"}},
+        ]
+    )
+    monitor = FillMonitor(client, poll_interval_seconds=0.001, max_wait_seconds=0.01)
+
+    result = await monitor.wait_for_terminal_fill(order_id)
+
+    assert result.timed_out
+    assert result.terminal_state is None
+    assert result.last_state is not None
+    assert result.last_state.status in {"open", "partial"}
+
+
+@pytest.mark.asyncio
+async def test_fill_monitor_uses_ws_status_for_fast_terminal_detection() -> None:
+    order_id = "order-3"
+    ws_provider = _FakeWsProvider(
+        states=[
+            OrderFillState(
+                order_id=order_id,
+                status="closed",
+                filled_volume=0.5,
+                avg_price=200.0,
+                updated_at=datetime.now(UTC),
+                source="ws",
+            )
+        ]
+    )
+    client = _FakePollClient(responses=[])
+    monitor = FillMonitor(
+        client,
+        poll_interval_seconds=0.001,
+        max_wait_seconds=0.1,
+        ws_status_provider=ws_provider.get,
+    )
+
+    result = await monitor.wait_for_terminal_fill(order_id)
+
+    assert not result.timed_out
+    assert result.terminal_state is not None
+    assert result.terminal_state.source == "ws"
+    assert client.calls == 0
+
+
+def test_fill_monitor_rejects_invalid_configuration() -> None:
+    client = _FakePollClient(responses=[])
+
+    with pytest.raises(ValueError, match="poll_interval_seconds"):
+        FillMonitor(client, poll_interval_seconds=0.0)
+
+    with pytest.raises(ValueError, match="max_wait_seconds"):
+        FillMonitor(client, max_wait_seconds=0.0)

tests/unit/test_idempotency.py

@@ -0,0 +1,109 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import UTC, datetime
+from typing import Any
+
+import pytest
+
+from arbitrade.detection.engine import OpportunityEvent
+from arbitrade.execution.idempotency import IdempotencyKeyFactory, OrderReconciler
+from arbitrade.execution.sequencer import ExecutionLeg
+
+
+@dataclass(slots=True)
+class _FakeHistoryClient:
+    response: dict[str, Any]
+
+    async def query_order(self, *, order_id: str, include_trades: bool = True) -> dict[str, Any]:
+        return self.response
+
+
+def _sample_event() -> OpportunityEvent:
+    return OpportunityEvent(
+        detected_at=datetime.now(UTC),
+        cycle="USD->BTC->ETH->USD",
+        updated_pair="BTC/USD",
+        gross_rate=1.02,
+        net_rate=1.01,
+        gross_pct=2.0,
+        net_pct=1.0,
+        est_profit=1.0,
+        allocated_capital=10.0,
+    )
+
+
+def test_idempotency_key_factory_is_deterministic() -> None:
+    factory = IdempotencyKeyFactory()
+    event = _sample_event()
+    leg = ExecutionLeg(
+        from_currency="USD",
+        to_currency="BTC",
+        pair="BTC/USD",
+        side="buy",
+        volume=10.0,
+    )
+
+    first = factory.user_ref_for_leg(event, leg, 0)
+    second = factory.user_ref_for_leg(event, leg, 0)
+
+    assert first == second
+    assert first > 0
+
+
+@pytest.mark.asyncio
+async def test_order_reconciler_maps_query_response_to_report() -> None:
+    client = _FakeHistoryClient(
+        response={
+            "order-1": {
+                "status": "closed",
+                "vol_exec": "5.0",
+                "price": "100.0",
+                "pair": "BTC/USD",
+                "type": "buy",
+                "userref": 12345,
+            }
+        }
+    )
+    reconciler = OrderReconciler(client)
+
+    report = await reconciler.reconcile_order(
+        order_id="order-1",
+        user_ref=12345,
+        expected_pair="BTC/USD",
+        expected_side="buy",
+        expected_volume=10.0,
+    )
+
+    assert report.is_terminal
+    assert report.matches_request
+    assert report.status == "closed"
+    assert report.filled_volume == 5.0
+    assert report.avg_price == 100.0
+
+
+@pytest.mark.asyncio
+async def test_order_reconciler_marks_mismatch() -> None:
+    client = _FakeHistoryClient(
+        response={
+            "order-1": {
+                "status": "closed",
+                "vol_exec": "5.0",
+                "price": "100.0",
+                "pair": "ETH/USD",
+                "type": "sell",
+                "userref": 999,
+            }
+        }
+    )
+    reconciler = OrderReconciler(client)
+
+    report = await reconciler.reconcile_order(
+        order_id="order-1",
+        user_ref=12345,
+        expected_pair="BTC/USD",
+        expected_side="buy",
+        expected_volume=10.0,
+    )
+
+    assert not report.matches_request

tests/unit/test_incremental_detector.py

@@ -0,0 +1,306 @@
+from datetime import UTC, datetime, timedelta
+
+import pytest
+
+from arbitrade.detection.engine import IncrementalCycleDetector
+from arbitrade.detection.graph import CurrencyGraph, TriangularCycle
+from arbitrade.exchange.models import BookLevel
+from arbitrade.market_data.order_book import OrderBook
+
+
+def _make_book(*, bid: float, ask: float) -> OrderBook:
+    book = OrderBook()
+    book.apply_bids([BookLevel(price=bid, volume=1.0)])
+    book.apply_asks([BookLevel(price=ask, volume=1.0)])
+    return book
+
+
+def _make_book_levels(
+    *, bids: list[tuple[float, float]], asks: list[tuple[float, float]]
+) -> OrderBook:
+    book = OrderBook()
+    book.apply_bids([BookLevel(price=price, volume=volume) for price, volume in bids])
+    book.apply_asks([BookLevel(price=price, volume=volume) for price, volume in asks])
+    return book
+
+
+def test_incremental_detector_scores_only_cycles_touched_by_pair() -> None:
+    cycle_a = TriangularCycle(
+        currencies=("USD", "BTC", "ETH"),
+        pairs=("BTC/USD", "ETH/BTC", "ETH/USD"),
+    )
+    cycle_b = TriangularCycle(
+        currencies=("USD", "BTC", "LTC"),
+        pairs=("BTC/USD", "LTC/BTC", "LTC/USD"),
+    )
+    cycle_c = TriangularCycle(
+        currencies=("USD", "SOL", "ADA"),
+        pairs=("SOL/USD", "ADA/SOL", "ADA/USD"),
+    )
+
+    cycles = [cycle_a, cycle_b, cycle_c]
+    index = CurrencyGraph.index_cycles_by_pair(cycles)
+    detector = IncrementalCycleDetector(index)
+
+    books = {
+        "BTC/USD": _make_book(bid=100.0, ask=100.0),
+        "ETH/BTC": _make_book(bid=0.05, ask=0.05),
+        "ETH/USD": _make_book(bid=5.20, ask=5.21),
+        "LTC/BTC": _make_book(bid=0.01, ask=0.01),
+        "LTC/USD": _make_book(bid=1.02, ask=1.03),
+        "SOL/USD": _make_book(bid=20.0, ask=20.1),
+        "ADA/SOL": _make_book(bid=0.02, ask=0.021),
+        "ADA/USD": _make_book(bid=0.42, ask=0.43),
+    }
+
+    scores = detector.score_updated_pair("BTC/USD", books)
+
+    assert len(scores) == 2
+    assert {score.cycle for score in scores} == {cycle_a, cycle_b}
+
+
+def test_incremental_detector_uses_best_bid_ask_for_gross_rate() -> None:
+    cycle = TriangularCycle(
+        currencies=("USD", "BTC", "ETH"),
+        pairs=("BTC/USD", "ETH/BTC", "ETH/USD"),
+    )
+    detector = IncrementalCycleDetector(CurrencyGraph.index_cycles_by_pair([cycle]))
+
+    books = {
+        "BTC/USD": _make_book(bid=99.9, ask=100.0),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.20, ask=5.21),
+    }
+
+    scores = detector.score_updated_pair("ETH/BTC", books)
+
+    assert len(scores) == 1
+    assert scores[0].gross_rate == 1.04
+    assert scores[0].net_rate == 1.04
+    assert scores[0].is_profitable
+
+
+def test_incremental_detector_applies_fees_to_net_rate() -> None:
+    cycle = TriangularCycle(
+        currencies=("USD", "BTC", "ETH"),
+        pairs=("BTC/USD", "ETH/BTC", "ETH/USD"),
+    )
+    detector = IncrementalCycleDetector(
+        CurrencyGraph.index_cycles_by_pair([cycle]),
+        fee_rate=0.001,
+    )
+
+    books = {
+        "BTC/USD": _make_book(bid=99.9, ask=100.0),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.20, ask=5.21),
+    }
+
+    scores = detector.score_updated_pair("ETH/BTC", books)
+
+    assert len(scores) == 1
+    assert scores[0].gross_rate == 1.04
+    assert scores[0].net_rate < scores[0].gross_rate
+
+
+def test_incremental_detector_uses_depth_and_slippage() -> None:
+    cycle = TriangularCycle(
+        currencies=("USD", "BTC", "ETH"),
+        pairs=("BTC/USD", "ETH/BTC", "ETH/USD"),
+    )
+    detector = IncrementalCycleDetector(
+        CurrencyGraph.index_cycles_by_pair([cycle]),
+        max_depth_levels=2,
+    )
+
+    books = {
+        "BTC/USD": _make_book_levels(
+            bids=[(99.9, 5.0)],
+            asks=[(100.0, 0.002), (101.0, 0.020)],
+        ),
+        "ETH/BTC": _make_book_levels(
+            bids=[(0.049, 5.0)],
+            asks=[(0.05, 0.5)],
+        ),
+        "ETH/USD": _make_book_levels(
+            bids=[(5.2, 5.0)],
+            asks=[(5.21, 5.0)],
+        ),
+    }
+
+    scores = detector.score_updated_pair("BTC/USD", books)
+
+    assert len(scores) == 1
+    assert scores[0].gross_rate < 1.04
+
+
+def test_incremental_detector_returns_no_score_on_insufficient_depth() -> None:
+    cycle = TriangularCycle(
+        currencies=("USD", "BTC", "ETH"),
+        pairs=("BTC/USD", "ETH/BTC", "ETH/USD"),
+    )
+    detector = IncrementalCycleDetector(
+        CurrencyGraph.index_cycles_by_pair([cycle]),
+        max_depth_levels=1,
+    )
+
+    books = {
+        "BTC/USD": _make_book_levels(
+            bids=[(99.9, 5.0)],
+            asks=[(100.0, 0.001)],
+        ),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.2, ask=5.21),
+    }
+
+    scores = detector.score_updated_pair("BTC/USD", books)
+
+    assert scores == []
+
+
+def test_incremental_detector_filters_below_profit_threshold() -> None:
+    cycle = TriangularCycle(
+        currencies=("USD", "BTC", "ETH"),
+        pairs=("BTC/USD", "ETH/BTC", "ETH/USD"),
+    )
+    detector = IncrementalCycleDetector(
+        CurrencyGraph.index_cycles_by_pair([cycle]),
+        min_profit_threshold=0.05,
+    )
+
+    books = {
+        "BTC/USD": _make_book(bid=99.9, ask=100.0),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.20, ask=5.21),
+    }
+
+    scores = detector.score_updated_pair("ETH/BTC", books)
+
+    assert scores == []
+
+
+def test_incremental_detector_enforces_min_order_size_by_pair() -> None:
+    cycle = TriangularCycle(
+        currencies=("USD", "BTC", "ETH"),
+        pairs=("BTC/USD", "ETH/BTC", "ETH/USD"),
+    )
+    detector = IncrementalCycleDetector(
+        CurrencyGraph.index_cycles_by_pair([cycle]),
+        min_order_size_by_pair={"BTC/USD": 0.02},
+    )
+
+    books = {
+        "BTC/USD": _make_book_levels(
+            bids=[(99.9, 5.0)],
+            asks=[(100.0, 0.005), (101.0, 0.005), (102.0, 0.005)],
+        ),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.2, ask=5.21),
+    }
+
+    scores = detector.score_updated_pair("BTC/USD", books)
+
+    assert scores == []
+
+
+def test_incremental_detector_rejects_stale_books() -> None:
+    cycle = TriangularCycle(
+        currencies=("USD", "BTC", "ETH"),
+        pairs=("BTC/USD", "ETH/BTC", "ETH/USD"),
+    )
+    detector = IncrementalCycleDetector(
+        CurrencyGraph.index_cycles_by_pair([cycle]),
+        max_book_age_seconds=1.0,
+    )
+
+    books = {
+        "BTC/USD": _make_book(bid=99.9, ask=100.0),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.20, ask=5.21),
+    }
+    books["ETH/BTC"]._updated_at = datetime.now(UTC) - timedelta(seconds=5)
+
+    scores = detector.score_updated_pair("ETH/BTC", books)
+
+    assert scores == []
+
+
+def test_incremental_detector_accepts_fresh_books_with_staleness_enabled() -> None:
+    cycle = TriangularCycle(
+        currencies=("USD", "BTC", "ETH"),
+        pairs=("BTC/USD", "ETH/BTC", "ETH/USD"),
+    )
+    detector = IncrementalCycleDetector(
+        CurrencyGraph.index_cycles_by_pair([cycle]),
+        max_book_age_seconds=5.0,
+    )
+
+    books = {
+        "BTC/USD": _make_book(bid=99.9, ask=100.0),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.20, ask=5.21),
+    }
+    now = datetime.now(UTC)
+    for book in books.values():
+        book._updated_at = now - timedelta(seconds=0.2)
+
+    scores = detector.score_updated_pair("ETH/BTC", books)
+
+    assert len(scores) == 1
+
+
+def test_incremental_detector_emits_structured_opportunity_event() -> None:
+    cycle = TriangularCycle(
+        currencies=("USD", "BTC", "ETH"),
+        pairs=("BTC/USD", "ETH/BTC", "ETH/USD"),
+    )
+    detector = IncrementalCycleDetector(
+        CurrencyGraph.index_cycles_by_pair([cycle]),
+        min_profit_threshold=0.01,
+    )
+
+    books = {
+        "BTC/USD": _make_book(bid=99.9, ask=100.0),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.20, ask=5.21),
+    }
+
+    opportunities = detector.opportunities_for_updated_pair(
+        "ETH/BTC",
+        books,
+        base_capital=500.0,
+    )
+
+    assert len(opportunities) == 1
+    event = opportunities[0]
+    assert event.cycle == "USD->BTC->ETH->USD"
+    assert event.updated_pair == "ETH/BTC"
+    assert event.gross_pct == pytest.approx(4.0)
+    assert event.net_pct == pytest.approx(4.0)
+    assert event.est_profit == pytest.approx(20.0)
+
+
+def test_incremental_detector_estimated_profit_scales_with_capital() -> None:
+    cycle = TriangularCycle(
+        currencies=("USD", "BTC", "ETH"),
+        pairs=("BTC/USD", "ETH/BTC", "ETH/USD"),
+    )
+    detector = IncrementalCycleDetector(
+        CurrencyGraph.index_cycles_by_pair([cycle]),
+        min_profit_threshold=0.0,
+    )
+
+    books = {
+        "BTC/USD": _make_book(bid=99.9, ask=100.0),
+        "ETH/BTC": _make_book(bid=0.049, ask=0.05),
+        "ETH/USD": _make_book(bid=5.20, ask=5.21),
+    }
+
+    opportunities = detector.opportunities_for_updated_pair(
+        "ETH/BTC",
+        books,
+        base_capital=250.0,
+    )
+
+    assert len(opportunities) == 1
+    assert opportunities[0].est_profit == pytest.approx(10.0)

tests/unit/test_kill_switch.py

@@ -0,0 +1,27 @@
+from __future__ import annotations
+
+from arbitrade.risk.kill_switch import KillSwitch
+
+
+def test_kill_switch_can_activate_and_deactivate() -> None:
+    kill_switch = KillSwitch()
+
+    assert not kill_switch.is_active
+    assert kill_switch.reason is None
+
+    kill_switch.activate(reason="manual")
+
+    assert kill_switch.is_active
+    assert kill_switch.reason == "manual"
+
+    kill_switch.deactivate()
+
+    assert not kill_switch.is_active
+    assert kill_switch.reason is None
+
+
+def test_kill_switch_active_on_init_sets_reason() -> None:
+    kill_switch = KillSwitch(active=True)
+
+    assert kill_switch.is_active
+    assert kill_switch.reason == "manual"

tests/unit/test_kraken_rest.py

@@ -0,0 +1,248 @@
+import httpx
+import pytest
+import respx
+
+from arbitrade.config.settings import Settings
+from arbitrade.exchange.kraken_rest import KrakenRestClient
+
+
+@pytest.mark.asyncio
+async def test_server_time_success() -> None:
+    settings = Settings(_env_file=None)
+    client = KrakenRestClient(settings)
+
+    with respx.mock(base_url=settings.kraken_rest_url) as mock_router:
+        mock_router.get("/0/public/Time").respond(
+            200,
+            json={"error": [], "result": {"unixtime": 1}},
+        )
+
+        payload = await client.server_time()
+
+    await client.close()
+    assert payload["unixtime"] == 1
+
+
+@pytest.mark.asyncio
+async def test_retry_then_success() -> None:
+    settings = Settings(
+        _env_file=None,
+        kraken_retry_attempts=2,
+        kraken_retry_base_delay_seconds=0.0,
+    )
+    client = KrakenRestClient(settings)
+
+    with respx.mock(base_url=settings.kraken_rest_url) as mock_router:
+        route = mock_router.get("/0/public/Time")
+        route.side_effect = [
+            httpx.ConnectError("boom"),
+            httpx.Response(200, json={"error": [], "result": {"unixtime": 2}}),
+        ]
+
+        payload = await client.server_time()
+
+    await client.close()
+    assert payload["unixtime"] == 2
+
+
+@pytest.mark.asyncio
+async def test_balances_private_call_uses_headers() -> None:
+    settings = Settings(
+        _env_file=None,
+        KRAKEN_API_KEY="key",
+        KRAKEN_API_SECRET="c2VjcmV0",  # base64("secret")
+        kraken_private_rate_limit_seconds=0.0,
+    )
+    client = KrakenRestClient(settings)
+
+    with respx.mock(base_url=settings.kraken_rest_url) as mock_router:
+        route = mock_router.post("/0/private/Balance").respond(
+            200,
+            json={"error": [], "result": {"ZUSD": "10.0"}},
+        )
+        payload = await client.balances()
+
+    await client.close()
+    request = route.calls.last.request
+    assert request.headers.get("API-Key") == "key"
+    assert request.headers.get("API-Sign")
+    assert payload["ZUSD"] == "10.0"
+
+
+@pytest.mark.asyncio
+async def test_balances_requires_credentials() -> None:
+    settings = Settings(
+        _env_file=None,
+        KRAKEN_API_KEY=None,
+        KRAKEN_API_SECRET=None,
+        kraken_private_rate_limit_seconds=0.0,
+    )
+    client = KrakenRestClient(settings)
+
+    with pytest.raises(RuntimeError, match="Missing Kraken API credentials"):
+        await client.balances()
+
+    await client.close()
+
+
+def test_compliance_default_ok() -> None:
+    settings = Settings(_env_file=None)
+    client = KrakenRestClient(settings)
+
+    issues = client.validate_compliance()
+
+    assert issues == []
+
+
+def test_compliance_detects_insecure_config() -> None:
+    settings = Settings(
+        _env_file=None,
+        KRAKEN_REST_URL="http://api.kraken.com",
+        KRAKEN_PRIVATE_RATE_LIMIT_SECONDS=0.0,
+        KRAKEN_RETRY_ATTEMPTS=0,
+        KRAKEN_RETRY_BASE_DELAY_SECONDS=-1.0,
+    )
+    client = KrakenRestClient(settings)
+
+    issues = client.validate_compliance()
+
+    assert any("https://" in issue for issue in issues)
+    assert any("below 1.0" in issue for issue in issues)
+    assert any("ATTEMPTS" in issue for issue in issues)
+    assert any("BASE_DELAY" in issue for issue in issues)
+
+
+@pytest.mark.asyncio
+async def test_place_market_order_posts_add_order_payload() -> None:
+    settings = Settings(
+        _env_file=None,
+        KRAKEN_API_KEY="key",
+        KRAKEN_API_SECRET="c2VjcmV0",  # base64("secret")
+        kraken_private_rate_limit_seconds=0.0,
+    )
+    client = KrakenRestClient(settings)
+
+    with respx.mock(base_url=settings.kraken_rest_url) as mock_router:
+        route = mock_router.post("/0/private/AddOrder").respond(
+            200,
+            json={"error": [], "result": {"txid": ["m1"]}},
+        )
+        payload = await client.place_market_order(
+            pair="XBTUSD",
+            side="buy",
+            volume=0.05,
+        )
+
+    await client.close()
+    request_body = route.calls.last.request.content.decode()
+    assert "pair=XBTUSD" in request_body
+    assert "type=buy" in request_body
+    assert "ordertype=market" in request_body
+    assert "volume=0.05" in request_body
+    assert payload["txid"] == ["m1"]
+
+
+@pytest.mark.asyncio
+async def test_place_limit_order_posts_add_order_payload() -> None:
+    settings = Settings(
+        _env_file=None,
+        KRAKEN_API_KEY="key",
+        KRAKEN_API_SECRET="c2VjcmV0",  # base64("secret")
+        kraken_private_rate_limit_seconds=0.0,
+    )
+    client = KrakenRestClient(settings)
+
+    with respx.mock(base_url=settings.kraken_rest_url) as mock_router:
+        route = mock_router.post("/0/private/AddOrder").respond(
+            200,
+            json={"error": [], "result": {"txid": ["l1"]}},
+        )
+        payload = await client.place_limit_order(
+            pair="ETHUSD",
+            side="sell",
+            volume=1.5,
+            price=3500.0,
+        )
+
+    await client.close()
+    request_body = route.calls.last.request.content.decode()
+    assert "pair=ETHUSD" in request_body
+    assert "type=sell" in request_body
+    assert "ordertype=limit" in request_body
+    assert "price=3500.0" in request_body
+    assert "volume=1.5" in request_body
+    assert payload["txid"] == ["l1"]
+
+
+@pytest.mark.asyncio
+async def test_place_order_validates_inputs() -> None:
+    settings = Settings(
+        _env_file=None,
+        KRAKEN_API_KEY="key",
+        KRAKEN_API_SECRET="c2VjcmV0",  # base64("secret")
+        kraken_private_rate_limit_seconds=0.0,
+    )
+    client = KrakenRestClient(settings)
+
+    with pytest.raises(ValueError, match="side"):
+        await client.place_market_order(pair="XBTUSD", side="hold", volume=0.1)
+
+    with pytest.raises(ValueError, match="volume"):
+        await client.place_market_order(pair="XBTUSD", side="buy", volume=0.0)
+
+    with pytest.raises(ValueError, match="price"):
+        await client.place_limit_order(
+            pair="XBTUSD",
+            side="buy",
+            volume=0.1,
+            price=0.0,
+        )
+
+    await client.close()
+
+
+@pytest.mark.asyncio
+async def test_query_order_posts_query_orders_payload() -> None:
+    settings = Settings(
+        _env_file=None,
+        KRAKEN_API_KEY="key",
+        KRAKEN_API_SECRET="c2VjcmV0",  # base64("secret")
+        kraken_private_rate_limit_seconds=0.0,
+    )
+    client = KrakenRestClient(settings)
+
+    with respx.mock(base_url=settings.kraken_rest_url) as mock_router:
+        route = mock_router.post("/0/private/QueryOrders").respond(
+            200,
+            json={"error": [], "result": {"order-1": {"status": "closed"}}},
+        )
+        payload = await client.query_order(order_id="order-1", include_trades=False)
+
+    await client.close()
+    request_body = route.calls.last.request.content.decode()
+    assert "txid=order-1" in request_body
+    assert "trades=false" in request_body
+    assert payload["order-1"]["status"] == "closed"
+
+
+@pytest.mark.asyncio
+async def test_cancel_order_posts_cancel_order_payload() -> None:
+    settings = Settings(
+        _env_file=None,
+        KRAKEN_API_KEY="key",
+        KRAKEN_API_SECRET="c2VjcmV0",  # base64("secret")
+        kraken_private_rate_limit_seconds=0.0,
+    )
+    client = KrakenRestClient(settings)
+
+    with respx.mock(base_url=settings.kraken_rest_url) as mock_router:
+        route = mock_router.post("/0/private/CancelOrder").respond(
+            200,
+            json={"error": [], "result": {"count": 1}},
+        )
+        payload = await client.cancel_order(order_id="order-1")
+
+    await client.close()
+    request_body = route.calls.last.request.content.decode()
+    assert "txid=order-1" in request_body
+    assert payload["count"] == 1

tests/unit/test_kraken_ws.py

@@ -0,0 +1,141 @@
+from __future__ import annotations
+
+import asyncio
+from dataclasses import dataclass, field
+from typing import Any
+
+import orjson
+import pytest
+
+from arbitrade.config.settings import Settings
+from arbitrade.exchange.kraken_ws import KrakenWsClient
+
+
+@dataclass(slots=True)
+class _FakeAlertNotifier:
+    events: list[dict[str, str]] = field(default_factory=list)
+
+    async def notify(
+        self,
+        *,
+        category: str,
+        severity: str,
+        title: str,
+        message: str,
+        details: dict[str, str] | None = None,
+    ) -> bool:
+        self.events.append(
+            {
+                "category": category,
+                "severity": severity,
+                "title": title,
+                "message": message,
+                **(details or {}),
+            }
+        )
+        return True
+
+
+class _FakeWebSocket:
+    def __init__(self, messages: list[Any]) -> None:
+        self._messages = messages
+
+    async def recv(self) -> str:
+        if not self._messages:
+            await asyncio.sleep(0)
+            return orjson.dumps({"channel": "heartbeat"}).decode("utf-8")
+        next_item = self._messages.pop(0)
+        if isinstance(next_item, Exception):
+            raise next_item
+        return next_item
+
+
+class _FakeConnectContext:
+    def __init__(self, ws: _FakeWebSocket) -> None:
+        self._ws = ws
+
+    async def __aenter__(self) -> _FakeWebSocket:
+        return self._ws
+
+    async def __aexit__(self, exc_type: object, exc: object, tb: object) -> bool:
+        return False
+
+
+def test_parse_book_delta() -> None:
+    client = KrakenWsClient(Settings())
+    message = {
+        "channel": "book",
+        "symbol": "BTC/USD",
+        "data": [
+            {
+                "bids": [{"price": "100.0", "qty": "1.2"}],
+                "asks": [{"price": "100.5", "qty": "0.8"}],
+                "checksum": 123,
+                "timestamp": 1717232000000,
+            }
+        ],
+    }
+
+    delta = client.parse_book_delta(message)
+
+    assert delta is not None
+    assert delta.symbol == "BTC/USD"
+    assert len(delta.bids) == 1
+    assert len(delta.asks) == 1
+    assert delta.checksum == 123
+
+
+@pytest.mark.asyncio
+async def test_connect_stream_emits_disconnect_and_reconnect_alerts(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    notifier = _FakeAlertNotifier()
+    settings = Settings(_env_file=None, WS_HEARTBEAT_TIMEOUT_SECONDS=1.0)
+    client = KrakenWsClient(settings, alert_notifier=notifier)
+
+    first_payload = orjson.dumps(
+        {"channel": "book", "symbol": "BTC/USD", "data": [{"bids": [], "asks": []}]}
+    ).decode("utf-8")
+    second_payload = orjson.dumps(
+        {"channel": "book", "symbol": "ETH/USD", "data": [{"bids": [], "asks": []}]}
+    ).decode("utf-8")
+
+    sessions = [
+        _FakeWebSocket([first_payload, RuntimeError("socket dropped")]),
+        _FakeWebSocket([second_payload]),
+    ]
+
+    def _fake_connect(*_args: object, **_kwargs: object) -> _FakeConnectContext:
+        return _FakeConnectContext(sessions.pop(0))
+
+    monkeypatch.setattr("arbitrade.exchange.kraken_ws.websockets.connect", _fake_connect)
+
+    stream = client.connect_stream()
+    first = await anext(stream)
+    second = await anext(stream)
+    await client.stop()
+    await stream.aclose()
+
+    assert first.payload["symbol"] == "BTC/USD"
+    assert second.payload["symbol"] == "ETH/USD"
+    titles = [event["title"] for event in notifier.events]
+    assert "WebSocket disconnected" in titles
+    assert "WebSocket reconnected" in titles
+
+
+@pytest.mark.asyncio
+async def test_recv_loop_emits_staleness_alert_on_timeout() -> None:
+    notifier = _FakeAlertNotifier()
+    settings = Settings(_env_file=None, WS_HEARTBEAT_TIMEOUT_SECONDS=0.001)
+    client = KrakenWsClient(settings, alert_notifier=notifier)
+
+    class _NeverReturnsWebSocket:
+        async def recv(self) -> str:
+            await asyncio.sleep(1)
+            return "{}"
+
+    with pytest.raises(TimeoutError):
+        await anext(client._recv_loop(_NeverReturnsWebSocket()))
+
+    assert len(notifier.events) == 1
+    assert notifier.events[0]["title"] == "WebSocket staleness abort"

tests/unit/test_latency_guardrails.py

@@ -0,0 +1,49 @@
+from __future__ import annotations
+
+from arbitrade.perf.guardrails import evaluate_guardrails
+from arbitrade.perf.latency import run_latency_profile
+
+
+def test_run_latency_profile_contains_expected_shape() -> None:
+    profile = run_latency_profile(iterations=50)
+
+    scenarios = profile.get("scenarios")
+    assert isinstance(scenarios, dict)
+    assert set(scenarios) == {
+        "book_update_burst",
+        "execution_spike",
+        "reconnect_storm",
+    }
+
+    for payload in scenarios.values():
+        assert isinstance(payload, dict)
+        stages = payload.get("stages")
+        assert isinstance(stages, dict)
+        assert "end_to_end" in stages
+
+
+def test_evaluate_guardrails_flags_regression() -> None:
+    baseline = {
+        "scenarios": {
+            "book_update_burst": {
+                "stages": {
+                    "end_to_end": {"p95_ms": 1.0, "p99_ms": 1.0},
+                }
+            }
+        }
+    }
+    current = {
+        "scenarios": {
+            "book_update_burst": {
+                "stages": {
+                    "end_to_end": {"p95_ms": 4.0, "p99_ms": 4.0},
+                }
+            }
+        }
+    }
+    thresholds = {"default": {"p95_ms": 2.0, "p99_ms": 2.0}}
+
+    failures = evaluate_guardrails(baseline=baseline, current=current, thresholds=thresholds)
+
+    assert failures
+    assert "latency regression" in failures[0]

tests/unit/test_loss_limits.py

@@ -0,0 +1,90 @@
+from __future__ import annotations
+
+import asyncio
+from datetime import UTC, datetime, timedelta
+from typing import Any
+
+import pytest
+
+from arbitrade.risk.loss_limits import LossLimitGuard
+
+
+class _FakeAlertNotifier:
+    def __init__(self) -> None:
+        self.events: list[dict[str, Any]] = []
+
+    async def notify(
+        self,
+        *,
+        category: str,
+        severity: str,
+        title: str,
+        message: str,
+        details: dict[str, str] | None = None,
+    ) -> bool:
+        self.events.append(
+            {
+                "category": category,
+                "severity": severity,
+                "title": title,
+                "message": message,
+                "details": details or {},
+            }
+        )
+        return True
+
+
+def test_loss_limit_guard_tracks_daily_and_cumulative_pnl() -> None:
+    guard = LossLimitGuard(daily_loss_limit=100.0, cumulative_loss_limit=200.0)
+    t0 = datetime.now(UTC)
+
+    guard.register_realized_pnl(-40.0, at=t0)
+    guard.register_realized_pnl(10.0, at=t0)
+
+    assert guard.cumulative_pnl == -30.0
+    assert guard.daily_pnl(t0.date()) == -30.0
+    assert not guard.is_halted
+
+
+def test_loss_limit_guard_halts_on_daily_limit() -> None:
+    guard = LossLimitGuard(daily_loss_limit=50.0)
+    t0 = datetime.now(UTC)
+
+    guard.register_realized_pnl(-30.0, at=t0)
+    guard.register_realized_pnl(-25.0, at=t0)
+
+    assert guard.is_halted
+    assert guard.halted_reason == "daily_loss_limit_breached"
+
+
+def test_loss_limit_guard_halts_on_cumulative_limit_across_days() -> None:
+    guard = LossLimitGuard(cumulative_loss_limit=60.0)
+    t0 = datetime.now(UTC)
+
+    guard.register_realized_pnl(-40.0, at=t0)
+    guard.register_realized_pnl(-25.0, at=t0 + timedelta(days=1))
+
+    assert guard.is_halted
+    assert guard.halted_reason == "cumulative_loss_limit_breached"
+
+
+def test_loss_limit_guard_rejects_invalid_limits() -> None:
+    with pytest.raises(ValueError, match="daily_loss_limit"):
+        LossLimitGuard(daily_loss_limit=0.0)
+
+    with pytest.raises(ValueError, match="cumulative_loss_limit"):
+        LossLimitGuard(cumulative_loss_limit=-1.0)
+
+
+@pytest.mark.asyncio
+async def test_loss_limit_guard_emits_alert_on_breach() -> None:
+    notifier = _FakeAlertNotifier()
+    guard = LossLimitGuard(daily_loss_limit=50.0, alert_notifier=notifier)
+
+    guard.register_realized_pnl(-60.0, at=datetime.now(UTC))
+    await asyncio.sleep(0)
+
+    assert guard.is_halted
+    assert len(notifier.events) == 1
+    assert notifier.events[0]["category"] == "threshold"
+    assert notifier.events[0]["title"] == "Daily loss limit breached"

tests/unit/test_market_data_feed.py

@@ -0,0 +1,484 @@
+from __future__ import annotations
+
+import asyncio
+from dataclasses import dataclass
+from datetime import UTC, datetime
+from types import SimpleNamespace
+
+import pytest
+
+from arbitrade.detection.engine import OpportunityEvent
+from arbitrade.exchange.models import BookDelta, BookLevel
+from arbitrade.market_data.feed import ExecutionOutcome, MarketDataFeed
+from arbitrade.risk.kill_switch import KillSwitch
+from arbitrade.risk.loss_limits import LossLimitGuard
+from arbitrade.risk.pre_trade import PreTradeValidator
+from arbitrade.risk.stop_conditions import StopConditionsGuard
+from arbitrade.risk.trade_limits import TradeLimitsGuard
+
+
+@dataclass(slots=True)
+class _FakeWsClient:
+    delta: BookDelta
+
+    async def connect_stream(self):
+        yield SimpleNamespace(payload={"channel": "book"})
+
+    def parse_book_delta(self, _payload: dict[str, object]) -> BookDelta:
+        return self.delta
+
+
+class _FakeSnapshotWriter:
+    def __init__(self) -> None:
+        self.items: list[object] = []
+
+    async def enqueue(self, snapshot: object) -> None:
+        self.items.append(snapshot)
+
+
+class _FakeOpportunityWriter:
+    def __init__(self) -> None:
+        self.items: list[OpportunityEvent] = []
+
+    async def enqueue(self, event: OpportunityEvent) -> None:
+        self.items.append(event)
+
+
+class _FakeDetector:
+    def __init__(self, event: OpportunityEvent) -> None:
+        self._event = event
+        self.last_base_capital: float | None = None
+
+    def opportunities_for_updated_pair(
+        self,
+        _updated_pair: str,
+        _books: dict[str, object],
+        *,
+        base_capital: float,
+    ):
+        self.last_base_capital = base_capital
+        return [self._event]
+
+
+class _FakeExecutor:
+    def __init__(self) -> None:
+        self.calls: list[OpportunityEvent] = []
+        self.realized_pnls: list[float | None] = []
+        self.outcomes: list[ExecutionOutcome] = []
+
+    async def execute(self, event: OpportunityEvent) -> ExecutionOutcome | float | None:
+        self.calls.append(event)
+        if self.outcomes:
+            return self.outcomes.pop(0)
+        if not self.realized_pnls:
+            return None
+        return self.realized_pnls.pop(0)
+
+
+class _FakeFailingExecutor:
+    def __init__(self) -> None:
+        self.calls: int = 0
+
+    async def execute(self, _event: OpportunityEvent) -> None:
+        self.calls += 1
+        raise RuntimeError("executor failure")
+
+
+class _FakeAlertNotifier:
+    def __init__(self) -> None:
+        self.events: list[dict[str, str]] = []
+
+    async def notify(
+        self,
+        *,
+        category: str,
+        severity: str,
+        title: str,
+        message: str,
+        details: dict[str, str] | None = None,
+    ) -> bool:
+        self.events.append(
+            {
+                "category": category,
+                "severity": severity,
+                "title": title,
+                "message": message,
+                **(details or {}),
+            }
+        )
+        return True
+
+
+@dataclass(slots=True)
+class _FakeWsClientTwoMessages:
+    delta: BookDelta
+
+    async def connect_stream(self):
+        yield SimpleNamespace(payload={"channel": "book", "seq": 1})
+        yield SimpleNamespace(payload={"channel": "book", "seq": 2})
+
+    def parse_book_delta(self, _payload: dict[str, object]) -> BookDelta:
+        return self.delta
+
+
+def _sample_event(*, allocated_capital: float = 1.0) -> OpportunityEvent:
+    return OpportunityEvent(
+        detected_at=datetime.now(UTC),
+        cycle="USD->BTC->ETH->USD",
+        updated_pair="BTC/USD",
+        gross_rate=1.04,
+        net_rate=1.03,
+        gross_pct=4.0,
+        net_pct=3.0,
+        est_profit=0.03,
+        allocated_capital=allocated_capital,
+    )
+
+
+def _sample_delta() -> BookDelta:
+    return BookDelta(
+        symbol="BTC/USD",
+        bids=[BookLevel(price=100.0, volume=1.0)],
+        asks=[BookLevel(price=100.5, volume=1.0)],
+    )
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_dry_run_does_not_execute_orders() -> None:
+    event = _sample_event()
+    executor = _FakeExecutor()
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClient(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=_FakeDetector(event),
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=True,
+        opportunity_executor=executor.execute,
+    )
+
+    await feed.run()
+
+    assert executor.calls == []
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_live_mode_executes_orders() -> None:
+    event = _sample_event()
+    executor = _FakeExecutor()
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClient(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=_FakeDetector(event),
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+    )
+
+    await feed.run()
+
+    assert len(executor.calls) == 1
+    assert executor.calls[0].cycle == "USD->BTC->ETH->USD"
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_enforces_per_trade_capital_limit() -> None:
+    event = _sample_event()
+    detector = _FakeDetector(event)
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClient(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=True,
+        trade_capital=250.0,
+        max_trade_capital=100.0,
+    )
+
+    await feed.run()
+
+    assert detector.last_base_capital == 100.0
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_auto_halts_on_daily_loss_limit() -> None:
+    event = _sample_event()
+    detector = _FakeDetector(event)
+    executor = _FakeExecutor()
+    executor.realized_pnls = [-60.0, -10.0]
+    loss_guard = LossLimitGuard(daily_loss_limit=50.0)
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClientTwoMessages(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        loss_limit_guard=loss_guard,
+    )
+
+    await feed.run()
+
+    assert len(executor.calls) == 1
+    assert loss_guard.is_halted
+    assert loss_guard.halted_reason == "daily_loss_limit_breached"
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_auto_halts_on_cumulative_loss_limit() -> None:
+    event = _sample_event()
+    detector = _FakeDetector(event)
+    executor = _FakeExecutor()
+    executor.realized_pnls = [-40.0, -15.0]
+    loss_guard = LossLimitGuard(cumulative_loss_limit=50.0)
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClientTwoMessages(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        loss_limit_guard=loss_guard,
+    )
+
+    await feed.run()
+
+    assert len(executor.calls) == 2
+    assert loss_guard.is_halted
+    assert loss_guard.halted_reason == "cumulative_loss_limit_breached"
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_enforces_max_concurrent_trades() -> None:
+    event = _sample_event()
+    detector = _FakeDetector(event)
+    executor = _FakeExecutor()
+    executor.outcomes = [ExecutionOutcome(realized_pnl=None, close_trade=False)]
+    trade_guard = TradeLimitsGuard(max_concurrent_trades=1)
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClientTwoMessages(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        trade_limits_guard=trade_guard,
+    )
+
+    await feed.run()
+
+    assert len(executor.calls) == 1
+    assert trade_guard.active_trades == 1
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_enforces_per_asset_exposure_cap() -> None:
+    event = _sample_event(allocated_capital=100.0)
+    detector = _FakeDetector(event)
+    executor = _FakeExecutor()
+    trade_guard = TradeLimitsGuard(max_exposure_per_asset=50.0)
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClient(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        trade_limits_guard=trade_guard,
+    )
+
+    await feed.run()
+
+    assert len(executor.calls) == 0
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_blocks_when_pre_trade_balance_insufficient() -> None:
+    event = _sample_event(allocated_capital=100.0)
+    detector = _FakeDetector(event)
+    executor = _FakeExecutor()
+    validator = PreTradeValidator(min_order_size_by_asset={"USD": 50.0})
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClient(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        pre_trade_validator=validator,
+        balance_provider=lambda: {"USD": 25.0},
+        quote_balance_asset="USD",
+    )
+
+    await feed.run()
+
+    assert len(executor.calls) == 0
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_blocks_when_pre_trade_min_order_not_met() -> None:
+    event = _sample_event(allocated_capital=25.0)
+    detector = _FakeDetector(event)
+    executor = _FakeExecutor()
+    validator = PreTradeValidator(min_order_size_by_asset={"USD": 50.0})
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClient(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        pre_trade_validator=validator,
+        balance_provider=lambda: {"USD": 500.0},
+        quote_balance_asset="USD",
+    )
+
+    await feed.run()
+
+    assert len(executor.calls) == 0
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_allows_when_pre_trade_validation_passes() -> None:
+    event = _sample_event(allocated_capital=75.0)
+    detector = _FakeDetector(event)
+    executor = _FakeExecutor()
+    validator = PreTradeValidator(min_order_size_by_asset={"USD": 50.0})
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClient(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        pre_trade_validator=validator,
+        balance_provider=lambda: {"USD": 500.0},
+        quote_balance_asset="USD",
+    )
+
+    await feed.run()
+
+    assert len(executor.calls) == 1
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_blocks_when_kill_switch_active() -> None:
+    event = _sample_event(allocated_capital=75.0)
+    detector = _FakeDetector(event)
+    executor = _FakeExecutor()
+    kill_switch = KillSwitch(active=True, reason="manual")
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClient(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        kill_switch=kill_switch,
+    )
+
+    await feed.run()
+
+    assert len(executor.calls) == 0
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_allows_when_kill_switch_inactive() -> None:
+    event = _sample_event(allocated_capital=75.0)
+    detector = _FakeDetector(event)
+    executor = _FakeExecutor()
+    kill_switch = KillSwitch(active=False)
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClient(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        kill_switch=kill_switch,
+    )
+
+    await feed.run()
+
+    assert len(executor.calls) == 1
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_halts_on_abnormal_source_latency() -> None:
+    event = _sample_event(allocated_capital=75.0)
+    detector = _FakeDetector(event)
+    executor = _FakeExecutor()
+    kill_switch = KillSwitch(active=False)
+    stop_guard = StopConditionsGuard(max_source_latency_ms=1.0)
+    delta = _sample_delta()
+    delta.source_timestamp_ms = 0
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClient(delta),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        kill_switch=kill_switch,
+        stop_conditions_guard=stop_guard,
+    )
+
+    await feed.run()
+
+    assert stop_guard.is_halted
+    assert stop_guard.halted_reason == "source_latency_limit_breached"
+    assert kill_switch.is_active
+    assert kill_switch.reason == "source_latency_limit_breached"
+    assert len(executor.calls) == 0
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_halts_on_repeated_execution_failures() -> None:
+    event = _sample_event(allocated_capital=75.0)
+    detector = _FakeDetector(event)
+    executor = _FakeFailingExecutor()
+    kill_switch = KillSwitch(active=False)
+    stop_guard = StopConditionsGuard(max_consecutive_failures=2)
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClientTwoMessages(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        kill_switch=kill_switch,
+        stop_conditions_guard=stop_guard,
+    )
+
+    await feed.run()
+
+    assert executor.calls == 2
+    assert stop_guard.is_halted
+    assert stop_guard.halted_reason == "consecutive_failures_limit_breached"
+    assert kill_switch.is_active
+    assert kill_switch.reason == "consecutive_failures_limit_breached"
+
+
+@pytest.mark.asyncio
+async def test_market_data_feed_emits_critical_alert_on_executor_exception() -> None:
+    event = _sample_event(allocated_capital=75.0)
+    detector = _FakeDetector(event)
+    executor = _FakeFailingExecutor()
+    notifier = _FakeAlertNotifier()
+    feed = MarketDataFeed(
+        ws_client=_FakeWsClient(_sample_delta()),
+        snapshot_writer=_FakeSnapshotWriter(),
+        detector=detector,
+        opportunity_writer=_FakeOpportunityWriter(),
+        paper_trading_mode=False,
+        opportunity_executor=executor.execute,
+        alert_notifier=notifier,
+    )
+
+    await feed.run()
+    await asyncio.sleep(0)
+
+    assert executor.calls == 1
+    assert len(notifier.events) == 1
+    assert notifier.events[0]["category"] == "system"
+    assert notifier.events[0]["severity"] == "critical"
+    assert notifier.events[0]["title"] == "Critical execution exception"

tests/unit/test_metrics.py

@@ -0,0 +1,144 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime, timedelta
+
+import pytest
+
+from arbitrade.config.settings import Settings
+from arbitrade.metrics import MetricsCalculator
+from arbitrade.storage.db import DuckDBStore
+
+
+def test_metrics_calculator_summarizes_execution_data(tmp_path) -> None:
+    settings = Settings(_env_file=None, DUCKDB_PATH=tmp_path / "metrics.duckdb")
+    store = DuckDBStore(settings)
+    store.migrate()
+
+    started = datetime.now(UTC)
+    finished = started + timedelta(seconds=30)
+    started_two = started + timedelta(minutes=1)
+    finished_two = started_two + timedelta(seconds=90)
+
+    with store.connect() as conn:
+        conn.execute(
+            """
+            INSERT INTO trades (
+                trade_ref,
+                started_at,
+                finished_at,
+                status,
+                realized_pnl,
+                estimated_pnl,
+                capital_used,
+                cycle,
+                leg_count
+            ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?), (?, ?, ?, ?, ?, ?, ?, ?, ?)
+            """,
+            [
+                "trade-1",
+                started,
+                finished,
+                "filled",
+                12.5,
+                10.0,
+                100.0,
+                "USD->BTC->ETH->USD",
+                3,
+                "trade-2",
+                started_two,
+                finished_two,
+                "filled",
+                -4.5,
+                -2.0,
+                200.0,
+                "USD->ETH->BTC->USD",
+                3,
+            ],
+        )
+        conn.execute(
+            """
+            INSERT INTO opportunities (
+                detected_at,
+                cycle,
+                gross_pct,
+                net_pct,
+                est_profit,
+                executed
+            ) VALUES (?, ?, ?, ?, ?, ?), (?, ?, ?, ?, ?, ?), (?, ?, ?, ?, ?, ?)
+            """,
+            [
+                started,
+                "USD->BTC->ETH->USD",
+                4.0,
+                3.0,
+                0.03,
+                True,
+                started_two,
+                "USD->ETH->BTC->USD",
+                2.0,
+                1.0,
+                0.01,
+                False,
+                started_two + timedelta(seconds=30),
+                "USD->BTC->ETH->USD",
+                5.0,
+                4.0,
+                0.04,
+                True,
+            ],
+        )
+        conn.execute(
+            """
+            INSERT INTO orders (
+                trade_ref,
+                order_ref,
+                leg_index,
+                pair,
+                side,
+                volume,
+                user_ref,
+                status,
+                filled_volume,
+                avg_price,
+                raw_response,
+                recorded_at
+            ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?), (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+            """,
+            [
+                "trade-1",
+                "order-1",
+                0,
+                "BTC/USD",
+                "buy",
+                2.0,
+                101,
+                "closed",
+                2.0,
+                100.0,
+                "{}",
+                started,
+                "trade-2",
+                "order-2",
+                0,
+                "ETH/USD",
+                "sell",
+                4.0,
+                202,
+                "closed",
+                3.0,
+                200.0,
+                "{}",
+                started_two,
+            ],
+        )
+
+    metrics = MetricsCalculator(store).compute()
+
+    assert metrics.realized_pnl_usd == 8.0
+    assert metrics.win_rate == 0.5
+    assert metrics.avg_trade_duration_seconds == 60.0
+    assert metrics.opportunities_per_minute == 2.0
+    assert metrics.fill_rate == 0.875
+    assert metrics.latency_p50_seconds == 60.0
+    assert metrics.latency_p95_seconds == 87.0
+    assert metrics.latency_p99_seconds == pytest.approx(89.4)

tests/unit/test_opportunity_writer.py

@@ -0,0 +1,48 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime
+
+import pytest
+
+from arbitrade.config.settings import Settings
+from arbitrade.detection.engine import OpportunityEvent
+from arbitrade.storage.db import DuckDBStore
+from arbitrade.storage.opportunities import AsyncOpportunityWriter
+from arbitrade.storage.repositories import OpportunityRepository
+
+
+@pytest.mark.asyncio
+async def test_async_opportunity_writer_persists_events(tmp_path) -> None:
+    settings = Settings(_env_file=None, DUCKDB_PATH=tmp_path / "test.duckdb")
+    store = DuckDBStore(settings)
+    store.migrate()
+
+    repository = OpportunityRepository(store)
+    writer = AsyncOpportunityWriter(repository, max_queue_size=10)
+    await writer.start()
+
+    event = OpportunityEvent(
+        detected_at=datetime.now(UTC),
+        cycle="USD->BTC->ETH->USD",
+        updated_pair="BTC/USD",
+        gross_rate=1.04,
+        net_rate=1.03,
+        gross_pct=4.0,
+        net_pct=3.0,
+        est_profit=0.03,
+    )
+
+    await writer.enqueue(event)
+    await writer.stop()
+
+    with store.connect() as conn:
+        rows = conn.execute(
+            "SELECT cycle, gross_pct, net_pct, est_profit, executed FROM opportunities"
+        ).fetchall()
+
+    assert len(rows) == 1
+    assert rows[0][0] == "USD->BTC->ETH->USD"
+    assert rows[0][1] == 4.0
+    assert rows[0][2] == 3.0
+    assert rows[0][3] == 0.03
+    assert rows[0][4] is False

tests/unit/test_order_book.py

@@ -0,0 +1,27 @@
+from arbitrade.exchange.models import BookLevel
+from arbitrade.market_data.order_book import OrderBook
+
+
+def test_order_book_apply_and_best_levels() -> None:
+    book = OrderBook()
+    book.apply_bids([BookLevel(price=100.0, volume=1.0), BookLevel(price=99.5, volume=2.0)])
+    book.apply_asks([BookLevel(price=100.5, volume=1.1), BookLevel(price=101.0, volume=0.9)])
+
+    best_bid = book.best_bid()
+    best_ask = book.best_ask()
+
+    assert best_bid is not None
+    assert best_ask is not None
+    assert best_bid.price == 100.0
+    assert best_ask.price == 100.5
+
+
+def test_order_book_checksum_matches_self() -> None:
+    book = OrderBook()
+    book.apply_bids([BookLevel(price=100.0, volume=1.0)])
+    book.apply_asks([BookLevel(price=100.5, volume=1.0)])
+
+    checksum = book.compute_checksum()
+
+    assert isinstance(checksum, int)
+    assert checksum == book.compute_checksum()

tests/unit/test_partial_fill_recovery.py

@@ -0,0 +1,96 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import UTC, datetime
+from typing import Any
+
+import pytest
+
+from arbitrade.execution.fill_monitor import FillMonitorResult, OrderFillState
+from arbitrade.execution.recovery import PartialFillRecovery
+
+
+@dataclass(slots=True)
+class _FakeRestClient:
+    cancel_calls: list[str] = None  # type: ignore[assignment]
+    market_calls: list[dict[str, Any]] = None  # type: ignore[assignment]
+
+    def __post_init__(self) -> None:
+        self.cancel_calls = []
+        self.market_calls = []
+
+    async def cancel_order(self, *, order_id: str) -> dict[str, Any]:
+        self.cancel_calls.append(order_id)
+        return {"result": {"count": 1}}
+
+    async def place_market_order(self, *, pair: str, side: str, volume: float) -> dict[str, Any]:
+        self.market_calls.append({"pair": pair, "side": side, "volume": volume})
+        return {"txid": ["hedge-1"]}
+
+
+def _monitor_result(
+    *, status: str, filled_volume: float | None, timed_out: bool
+) -> FillMonitorResult:
+    state = OrderFillState(
+        order_id="order-1",
+        status=status,
+        filled_volume=filled_volume,
+        avg_price=100.0,
+        updated_at=datetime.now(UTC),
+        source="rest_poll",
+    )
+    return FillMonitorResult(
+        order_id="order-1",
+        timed_out=timed_out,
+        terminal_state=None if status in {"open", "partial"} else state,
+        last_state=state,
+        elapsed_seconds=1.0,
+    )
+
+
+@pytest.mark.asyncio
+async def test_partial_fill_recovery_cancels_open_order_and_hedges_residual() -> None:
+    client = _FakeRestClient()
+    recovery = PartialFillRecovery(client)
+
+    result = await recovery.recover_partial_fill(
+        order_id="order-1",
+        pair="BTC/USD",
+        side="buy",
+        requested_volume=10.0,
+        fill_result=_monitor_result(status="partial", filled_volume=4.0, timed_out=True),
+    )
+
+    assert result.canceled
+    assert result.hedged
+    assert client.cancel_calls == ["order-1"]
+    assert client.market_calls == [{"pair": "BTC/USD", "side": "sell", "volume": 6.0}]
+    assert result.hedge_volume == 6.0
+    assert result.reason == "canceled_partial_order"
+
+
+@pytest.mark.asyncio
+async def test_partial_fill_recovery_no_hedge_when_no_residual() -> None:
+    client = _FakeRestClient()
+    recovery = PartialFillRecovery(client)
+
+    result = await recovery.recover_partial_fill(
+        order_id="order-1",
+        pair="BTC/USD",
+        side="sell",
+        requested_volume=5.0,
+        fill_result=_monitor_result(status="closed", filled_volume=5.0, timed_out=False),
+    )
+
+    assert not result.canceled
+    assert not result.hedged
+    assert client.cancel_calls == []
+    assert client.market_calls == []
+
+
+def test_partial_fill_recovery_rejects_invalid_volume() -> None:
+    client = _FakeRestClient()
+    recovery = PartialFillRecovery(client)
+
+    with pytest.raises(ValueError, match="requested_volume"):
+        recovery._residual_volume(None, 0.0)

tests/unit/test_pre_trade.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+import pytest
+
+from arbitrade.risk.pre_trade import PreTradeValidator
+
+
+def test_pre_trade_validator_accepts_when_balance_and_min_size_pass() -> None:
+    validator = PreTradeValidator(min_order_size_by_asset={"USD": 50.0})
+
+    assert validator.validate(
+        balances_by_asset={"USD": 100.0},
+        required_by_asset={"USD": 75.0},
+    )
+
+
+def test_pre_trade_validator_rejects_when_balance_insufficient() -> None:
+    validator = PreTradeValidator(min_order_size_by_asset={"USD": 50.0})
+
+    assert not validator.validate(
+        balances_by_asset={"USD": 40.0},
+        required_by_asset={"USD": 75.0},
+    )
+
+
+def test_pre_trade_validator_rejects_when_below_min_size() -> None:
+    validator = PreTradeValidator(min_order_size_by_asset={"USD": 50.0})
+
+    assert not validator.validate(
+        balances_by_asset={"USD": 100.0},
+        required_by_asset={"USD": 30.0},
+    )
+
+
+def test_pre_trade_validator_rejects_invalid_min_order_size_config() -> None:
+    with pytest.raises(ValueError, match="minimum order size"):
+        PreTradeValidator(min_order_size_by_asset={"USD": 0.0})

tests/unit/test_runtime_lifecycle.py

@@ -0,0 +1,140 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import UTC, datetime
+
+import pytest
+
+from arbitrade.api.app import create_app
+from arbitrade.config.settings import Settings
+from arbitrade.runtime.lifecycle import (
+    graceful_shutdown,
+    persist_runtime_snapshot,
+    restore_runtime_state,
+)
+from arbitrade.storage.repositories import RuntimeStateRecord
+
+
+@dataclass(slots=True)
+class _FakeWorker:
+    stopped: bool = False
+
+    async def stop(self) -> None:
+        self.stopped = True
+
+
+@dataclass(slots=True)
+class _FakeStartupReconciler:
+    called: bool = False
+
+    async def reconcile_open_trades(self) -> None:
+        self.called = True
+
+
+@pytest.mark.asyncio
+async def test_persist_runtime_snapshot_writes_record(tmp_path) -> None:
+    app = create_app(Settings(_env_file=None, DUCKDB_PATH=tmp_path / "runtime.duckdb"))
+
+    app.state.dashboard_controls.is_running = True
+    app.state.dashboard_controls.kill_switch.deactivate()
+
+    snapshot = persist_runtime_snapshot(app, note="unit-test")
+
+    assert snapshot is not None
+    assert snapshot.note == "unit-test"
+
+    latest = app.state.runtime_state_repository.latest()
+    assert latest is not None
+    assert latest.note == "unit-test"
+    assert latest.is_running is True
+
+
+@pytest.mark.asyncio
+async def test_restore_runtime_state_applies_snapshot(tmp_path) -> None:
+    app = create_app(Settings(_env_file=None, DUCKDB_PATH=tmp_path / "restore.duckdb"))
+    app.state.runtime_state_repository.insert(
+        RuntimeStateRecord(
+            snapshot_at=datetime.now(UTC),
+            is_running=False,
+            kill_switch_active=True,
+            kill_switch_reason="manual-stop",
+            open_trade_count=0,
+            last_known_balances={"USD": 100.0},
+            note="seed",
+        )
+    )
+
+    report = await restore_runtime_state(app)
+
+    assert report.restored_from_snapshot is True
+    assert app.state.dashboard_controls.is_running is False
+    assert app.state.dashboard_controls.kill_switch.is_active is True
+    assert app.state.dashboard_controls.kill_switch.reason == "manual-stop"
+
+
+@pytest.mark.asyncio
+async def test_restore_runtime_state_enables_restart_guard_for_open_trades(tmp_path) -> None:
+    app = create_app(Settings(_env_file=None, DUCKDB_PATH=tmp_path / "open-trades.duckdb"))
+
+    with app.state.store.connect() as conn:
+        conn.execute(
+            """
+            INSERT INTO trades (
+                trade_ref,
+                started_at,
+                finished_at,
+                status,
+                realized_pnl,
+                estimated_pnl,
+                capital_used,
+                cycle,
+                leg_count
+            ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+            """,
+            [
+                "open-trade-1",
+                datetime.now(UTC),
+                None,
+                "open",
+                None,
+                1.0,
+                100.0,
+                "USD->BTC->ETH->USD",
+                3,
+            ],
+        )
+
+    report = await restore_runtime_state(app)
+
+    assert report.open_trades_detected == 1
+    assert report.restart_guard_active is True
+    assert app.state.dashboard_controls.is_running is False
+    assert app.state.dashboard_controls.kill_switch.is_active is True
+    assert app.state.dashboard_controls.kill_switch.reason == "recovery_open_trades_detected"
+
+
+@pytest.mark.asyncio
+async def test_graceful_shutdown_drains_workers_and_persists_snapshot(tmp_path) -> None:
+    app = create_app(Settings(_env_file=None, DUCKDB_PATH=tmp_path / "shutdown.duckdb"))
+    worker = _FakeWorker()
+    app.state.background_workers = [worker]
+    app.state.dashboard_controls.is_running = True
+
+    await graceful_shutdown(app)
+
+    assert worker.stopped is True
+    assert app.state.dashboard_controls.is_running is False
+    latest = app.state.runtime_state_repository.latest()
+    assert latest is not None
+    assert latest.note == "graceful_shutdown"
+
+
+@pytest.mark.asyncio
+async def test_restore_runtime_state_calls_startup_reconciler(tmp_path) -> None:
+    app = create_app(Settings(_env_file=None, DUCKDB_PATH=tmp_path / "reconciler.duckdb"))
+    reconciler = _FakeStartupReconciler()
+    app.state.startup_reconciler = reconciler
+
+    await restore_runtime_state(app)
+
+    assert reconciler.called is True

tests/unit/test_settings_validation.py

@@ -0,0 +1,55 @@
+import pytest
+from pydantic import ValidationError
+
+from arbitrade.config.settings import Settings
+
+
+def test_dashboard_auth_requires_both_fields() -> None:
+    with pytest.raises(ValidationError):
+        Settings(_env_file=None, DASHBOARD_AUTH_USERNAME="admin")
+
+
+def test_kraken_api_auth_requires_key_and_secret() -> None:
+    with pytest.raises(ValidationError):
+        Settings(
+            _env_file=None,
+            KRAKEN_API_KEY="key-only",
+            KRAKEN_API_SECRET="",
+        )
+
+
+def test_kraken_permissions_require_query_and_trade() -> None:
+    with pytest.raises(ValidationError):
+        Settings(
+            _env_file=None,
+            KRAKEN_API_KEY="k",
+            KRAKEN_API_SECRET="s",
+            KRAKEN_API_KEY_PERMISSIONS="query",
+        )
+
+
+def test_kraken_permissions_forbid_withdrawal_scope() -> None:
+    with pytest.raises(ValidationError):
+        Settings(
+            _env_file=None,
+            KRAKEN_API_KEY="k",
+            KRAKEN_API_SECRET="s",
+            KRAKEN_API_KEY_PERMISSIONS="query,trade,withdraw",
+        )
+
+
+def test_alert_min_severity_is_validated() -> None:
+    with pytest.raises(ValidationError):
+        Settings(_env_file=None, ALERT_MIN_SEVERITY="nope")
+
+
+def test_valid_security_configuration_passes() -> None:
+    settings = Settings(
+        _env_file=None,
+        KRAKEN_API_KEY="k",
+        KRAKEN_API_SECRET="s",
+        KRAKEN_API_KEY_PERMISSIONS="query,trade",
+        ALERT_MIN_SEVERITY="warning",
+    )
+
+    assert settings.kraken_api_key_permissions == "query,trade"

tests/unit/test_stop_conditions.py

@@ -0,0 +1,99 @@
+from __future__ import annotations
+
+import asyncio
+from typing import Any
+
+import pytest
+
+from arbitrade.risk.stop_conditions import StopConditionsGuard
+
+
+class _FakeAlertNotifier:
+    def __init__(self) -> None:
+        self.events: list[dict[str, Any]] = []
+
+    async def notify(
+        self,
+        *,
+        category: str,
+        severity: str,
+        title: str,
+        message: str,
+        details: dict[str, str] | None = None,
+    ) -> bool:
+        self.events.append(
+            {
+                "category": category,
+                "severity": severity,
+                "title": title,
+                "message": message,
+                "details": details or {},
+            }
+        )
+        return True
+
+
+def test_stop_conditions_guard_halts_on_source_latency_breach() -> None:
+    guard = StopConditionsGuard(max_source_latency_ms=50.0)
+
+    guard.observe_latency(source_latency_ms=75.0, apply_latency_ms=1.0)
+
+    assert guard.is_halted
+    assert guard.halted_reason == "source_latency_limit_breached"
+
+
+def test_stop_conditions_guard_halts_on_apply_latency_breach() -> None:
+    guard = StopConditionsGuard(max_apply_latency_ms=2.0)
+
+    guard.observe_latency(source_latency_ms=None, apply_latency_ms=3.5)
+
+    assert guard.is_halted
+    assert guard.halted_reason == "apply_latency_limit_breached"
+
+
+def test_stop_conditions_guard_halts_on_consecutive_failures() -> None:
+    guard = StopConditionsGuard(max_consecutive_failures=2)
+
+    guard.register_failure()
+    assert not guard.is_halted
+
+    guard.register_failure()
+
+    assert guard.is_halted
+    assert guard.halted_reason == "consecutive_failures_limit_breached"
+
+
+def test_stop_conditions_guard_resets_failures_after_success() -> None:
+    guard = StopConditionsGuard(max_consecutive_failures=3)
+
+    guard.register_failure()
+    guard.register_success()
+    guard.register_failure()
+
+    assert guard.consecutive_failures == 1
+    assert not guard.is_halted
+
+
+def test_stop_conditions_guard_rejects_invalid_configuration() -> None:
+    with pytest.raises(ValueError, match="max_source_latency_ms"):
+        StopConditionsGuard(max_source_latency_ms=0.0)
+
+    with pytest.raises(ValueError, match="max_apply_latency_ms"):
+        StopConditionsGuard(max_apply_latency_ms=-1.0)
+
+    with pytest.raises(ValueError, match="max_consecutive_failures"):
+        StopConditionsGuard(max_consecutive_failures=0)
+
+
+@pytest.mark.asyncio
+async def test_stop_conditions_guard_emits_alert_on_failure_threshold() -> None:
+    notifier = _FakeAlertNotifier()
+    guard = StopConditionsGuard(max_consecutive_failures=1, alert_notifier=notifier)
+
+    guard.register_failure()
+    await asyncio.sleep(0)
+
+    assert guard.is_halted
+    assert len(notifier.events) == 1
+    assert notifier.events[0]["category"] == "threshold"
+    assert notifier.events[0]["title"] == "Consecutive failures limit breached"

tests/unit/test_trade_limits.py

@@ -0,0 +1,84 @@
+from __future__ import annotations
+
+import asyncio
+from typing import Any
+
+import pytest
+
+from arbitrade.risk.trade_limits import TradeLimitsGuard
+
+
+class _FakeAlertNotifier:
+    def __init__(self) -> None:
+        self.events: list[dict[str, Any]] = []
+
+    async def notify(
+        self,
+        *,
+        category: str,
+        severity: str,
+        title: str,
+        message: str,
+        details: dict[str, str] | None = None,
+    ) -> bool:
+        self.events.append(
+            {
+                "category": category,
+                "severity": severity,
+                "title": title,
+                "message": message,
+                "details": details or {},
+            }
+        )
+        return True
+
+
+def test_trade_limits_guard_blocks_when_max_concurrent_reached() -> None:
+    guard = TradeLimitsGuard(max_concurrent_trades=1)
+
+    guard.open_trade({"BTC": 10.0})
+
+    assert not guard.is_trade_allowed({"BTC": 1.0})
+
+
+def test_trade_limits_guard_blocks_when_asset_exposure_would_breach_cap() -> None:
+    guard = TradeLimitsGuard(max_exposure_per_asset=100.0)
+
+    guard.open_trade({"BTC": 80.0})
+
+    assert not guard.is_trade_allowed({"BTC": 25.0})
+    assert guard.is_trade_allowed({"ETH": 25.0})
+
+
+def test_trade_limits_guard_releases_exposure_on_close() -> None:
+    guard = TradeLimitsGuard(max_concurrent_trades=2, max_exposure_per_asset=100.0)
+
+    guard.open_trade({"BTC": 80.0})
+    guard.close_trade({"BTC": 80.0})
+
+    assert guard.active_trades == 0
+    assert guard.exposure_for_asset("BTC") == 0.0
+    assert guard.is_trade_allowed({"BTC": 100.0})
+
+
+def test_trade_limits_guard_rejects_invalid_configuration() -> None:
+    with pytest.raises(ValueError, match="max_concurrent_trades"):
+        TradeLimitsGuard(max_concurrent_trades=0)
+
+    with pytest.raises(ValueError, match="max_exposure_per_asset"):
+        TradeLimitsGuard(max_exposure_per_asset=0.0)
+
+
+@pytest.mark.asyncio
+async def test_trade_limits_guard_emits_alert_when_rejecting_trade() -> None:
+    notifier = _FakeAlertNotifier()
+    guard = TradeLimitsGuard(max_concurrent_trades=1, alert_notifier=notifier)
+
+    guard.open_trade({"BTC": 10.0})
+    allowed = guard.is_trade_allowed({"BTC": 1.0})
+    await asyncio.sleep(0)
+
+    assert not allowed
+    assert len(notifier.events) == 1
+    assert notifier.events[0]["category"] == "threshold"
+    assert notifier.events[0]["title"] == "Concurrent trade limit reached"

web/templates/base.html

@@ -3,44 +3,146 @@
   <head>
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />
-    <title>{{ title or "Arbitrade" }}</title>
+    <title>{% block title %}{{ title or "Arbitrade" }}{% endblock %}</title>
     <script src="https://unpkg.com/htmx.org@1.9.12"></script>
+    {% block head_scripts %}{% endblock %}
     <style>
-      :root {
-        --bg: #f4f7f5;
-        --ink: #122118;
-        --accent: #1f7a4c;
-        --card: #ffffff;
-      }
       body {
         margin: 0;
-        font-family: "Segoe UI", sans-serif;
-        color: var(--ink);
-        background: radial-gradient(circle at top, #e9f7ef, var(--bg));
+        font-family: Arial, sans-serif;
+        background: #0b1220;
+        color: #e5eefb;
       }
-      .wrap {
-        max-width: 720px;
-        margin: 4rem auto;
-        padding: 0 1rem;
+      .shell {
+        max-width: 1120px;
+        margin: 0 auto;
+        padding: 32px 20px 48px;
+      }
+      .hero {
+        display: flex;
+        justify-content: space-between;
+        gap: 24px;
+        align-items: end;
+        margin-bottom: 24px;
+      }
+      .title {
+        font-size: 2rem;
+        margin: 0 0 8px;
+      }
+      .subtitle {
+        margin: 0;
+        color: #9fb2d0;
+      }
+      .panel {
+        background: rgba(255, 255, 255, 0.04);
+        border: 1px solid rgba(255, 255, 255, 0.08);
+        border-radius: 16px;
+        padding: 20px;
+      }
+      .grid {
+        display: grid;
+        gap: 16px;
+        grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
       }
       .card {
-        background: var(--card);
-        border: 1px solid #d8e7dd;
-        border-radius: 12px;
-        padding: 1.25rem;
-        box-shadow: 0 6px 24px rgba(18, 33, 24, 0.08);
+        background: rgba(255, 255, 255, 0.04);
+        border-radius: 14px;
+        padding: 16px;
+        border: 1px solid rgba(255, 255, 255, 0.08);
       }
-      .badge {
-        display: inline-block;
-        background: #d9f3e5;
-        color: var(--accent);
-        border-radius: 999px;
-        padding: 0.2rem 0.6rem;
+      .label {
+        color: #9fb2d0;
+        font-size: 0.85rem;
+        margin-bottom: 8px;
+      }
+      .value {
+        font-size: 1.4rem;
+        font-weight: 700;
+      }
+      .meta {
+        margin-top: 18px;
+        color: #7f95b7;
         font-size: 0.85rem;
       }
+      .toolbar {
+        display: flex;
+        gap: 12px;
+        flex-wrap: wrap;
+      }
+      .toolbar form {
+        margin: 0;
+      }
+      .button {
+        display: inline-flex;
+        align-items: center;
+        justify-content: center;
+        border: 0;
+        cursor: pointer;
+        padding: 10px 14px;
+        border-radius: 999px;
+        background: #2d6cdf;
+        color: white;
+        text-decoration: none;
+        font: inherit;
+      }
+      .button.secondary {
+        background: transparent;
+        border: 1px solid rgba(255, 255, 255, 0.14);
+      }
+      .button.danger {
+        background: #ba3d4f;
+      }
+      .form-grid {
+        display: grid;
+        gap: 12px;
+      }
+      .field {
+        display: grid;
+        gap: 6px;
+        color: #9fb2d0;
+        font-size: 0.9rem;
+      }
+      .field input {
+        width: 100%;
+        box-sizing: border-box;
+        padding: 10px 12px;
+        border-radius: 10px;
+        border: 1px solid rgba(255, 255, 255, 0.14);
+        background: rgba(255, 255, 255, 0.04);
+        color: #e5eefb;
+        font: inherit;
+      }
+      .field.checkbox {
+        display: flex;
+        align-items: center;
+        gap: 8px;
+      }
+      .field.checkbox input {
+        width: auto;
+      }
+      .control-actions {
+        display: flex;
+        gap: 12px;
+        flex-wrap: wrap;
+      }
+      .chart-head {
+        display: flex;
+        justify-content: space-between;
+        align-items: center;
+        gap: 12px;
+        flex-wrap: wrap;
+      }
+      .chart-canvas {
+        width: 100%;
+        min-height: 260px;
+      }
     </style>
+    {% block extra_style %}{% endblock %}
   </head>
   <body>
-    <main class="wrap">{% block content %}{% endblock %}</main>
+    <main class="{% block main_class %}shell{% endblock %}">
+      {% block content %}{% endblock %}
+    </main>
+    {% block scripts %}{% endblock %}
   </body>
 </html>

web/templates/dashboard.html

@@ -0,0 +1,179 @@
+{% extends "base.html" %} {% block title %}{{ title }}{% endblock %} {% block
+head_scripts %}
+<script defer src="https://unpkg.com/alpinejs@3.x.x/dist/cdn.min.js"></script>
+<script src="https://cdn.jsdelivr.net/npm/chart.js@4.4.3/dist/chart.umd.min.js"></script>
+{% endblock %} {% block main_class %}shell{% endblock %} {% block content %}
+<section class="hero">
+  <div>
+    <h1 class="title">Arbitrade Dashboard</h1>
+    <p class="subtitle">Live execution, P&amp;L, and system state.</p>
+  </div>
+  <div class="toolbar">
+    <a
+      class="button"
+      href="{{ metrics_endpoint }}"
+      hx-get="{{ metrics_endpoint }}"
+      hx-target="#metrics-panel"
+      hx-swap="outerHTML"
+      >Refresh metrics</a
+    >
+    <a class="button secondary" href="/health">Health</a>
+  </div>
+</section>
+
+<section
+  id="metrics-shell"
+  hx-get="{{ metrics_endpoint }}"
+  hx-target="this"
+  hx-trigger="load, every 15s"
+  hx-swap="outerHTML"
+>
+  {% include "partials/metrics.html" %}
+</section>
+
+<section
+  id="overview-shell"
+  hx-get="{{ overview_endpoint }}"
+  hx-target="this"
+  hx-trigger="load, every 10s"
+  hx-swap="outerHTML"
+>
+  {% include "partials/overview.html" %}
+</section>
+
+<section
+  id="controls-shell"
+  hx-get="{{ controls_endpoint }}"
+  hx-target="this"
+  hx-trigger="load, every 20s"
+  hx-swap="outerHTML"
+>
+  {% include "partials/controls.html" %}
+</section>
+
+<section
+  id="charts-shell"
+  hx-get="{{ charts_endpoint }}"
+  hx-target="this"
+  hx-trigger="load, every 30s"
+  hx-swap="outerHTML"
+>
+  {% include "partials/charts.html" %}
+</section>
+
+<section
+  id="audit-shell"
+  hx-get="{{ audit_endpoint }}"
+  hx-target="this"
+  hx-trigger="load, every 20s"
+  hx-swap="outerHTML"
+>
+  {% include "partials/audit.html" %}
+</section>
+{% endblock %} {% block scripts %}
+<script>
+  window.arbitradeRenderCharts = (payload) => {
+    const chartHost = document.getElementById("opportunity-chart");
+    if (!chartHost || typeof Chart === "undefined") {
+      return;
+    }
+
+    const existing = Chart.getChart(chartHost);
+    if (existing) {
+      existing.destroy();
+    }
+
+    const data = JSON.parse(payload);
+    if (!data.has_chart_data) {
+      return;
+    }
+
+    new Chart(chartHost, {
+      type: "line",
+      data: {
+        labels: data.labels,
+        datasets: [
+          {
+            label: "Net %",
+            data: data.net_pct_values,
+            borderColor: "#2d6cdf",
+            backgroundColor: "rgba(45, 108, 223, 0.18)",
+            tension: 0.3,
+            fill: true,
+            yAxisID: "y",
+          },
+          {
+            label: "Est profit USD",
+            data: data.est_profit_values,
+            borderColor: "#52c41a",
+            backgroundColor: "rgba(82, 196, 26, 0.12)",
+            tension: 0.3,
+            fill: false,
+            yAxisID: "y1",
+          },
+        ],
+      },
+      options: {
+        responsive: true,
+        maintainAspectRatio: false,
+        interaction: {
+          mode: "index",
+          intersect: false,
+        },
+        plugins: {
+          legend: {
+            labels: {
+              color: "#e5eefb",
+            },
+          },
+        },
+        scales: {
+          x: {
+            ticks: {
+              color: "#9fb2d0",
+              maxRotation: 0,
+              autoSkip: true,
+            },
+            grid: {
+              color: "rgba(255, 255, 255, 0.06)",
+            },
+          },
+          y: {
+            position: "left",
+            ticks: {
+              color: "#9fb2d0",
+            },
+            grid: {
+              color: "rgba(255, 255, 255, 0.06)",
+            },
+          },
+          y1: {
+            position: "right",
+            ticks: {
+              color: "#9fb2d0",
+            },
+            grid: {
+              drawOnChartArea: false,
+            },
+          },
+        },
+      },
+    });
+  };
+
+  const stream = new EventSource("{{ stream_endpoint }}");
+  stream.addEventListener("metrics", (event) => {
+    const panel = document.getElementById("metrics-panel");
+    if (panel) {
+      panel.outerHTML = JSON.parse(event.data);
+    }
+  });
+  const overviewStream = new EventSource("{{ overview_stream_endpoint }}");
+  overviewStream.addEventListener("overview", (event) => {
+    const panel = document.getElementById("overview-panel");
+    if (panel) {
+      panel.outerHTML = JSON.parse(event.data);
+    }
+  });
+</script>
+{% endblock %}

web/templates/partials/audit.html

@@ -0,0 +1,37 @@
+<div id="audit-panel" class="panel" style="margin-top: 16px">
+  <div class="label">Audit Trail</div>
+  <div class="meta">Generated {{ generated_at }}</div>
+
+  <div style="overflow-x: auto; margin-top: 12px">
+    <table style="width: 100%; border-collapse: collapse; font-size: 0.9rem">
+      <thead>
+        <tr>
+          <th style="text-align: left; padding: 8px">Time</th>
+          <th style="text-align: left; padding: 8px">Actor</th>
+          <th style="text-align: left; padding: 8px">Event</th>
+          <th style="text-align: left; padding: 8px">Decision</th>
+          <th style="text-align: left; padding: 8px">Payload</th>
+          <th style="text-align: left; padding: 8px">Correlation</th>
+        </tr>
+      </thead>
+      <tbody>
+        {% if entries %}
+        {% for entry in entries %}
+        <tr>
+          <td style="padding: 8px; color: #9fb2d0">{{ entry.occurred_at }}</td>
+          <td style="padding: 8px">{{ entry.actor }}</td>
+          <td style="padding: 8px">{{ entry.event_type }}</td>
+          <td style="padding: 8px">{{ entry.decision }}</td>
+          <td style="padding: 8px; color: #9fb2d0">{{ entry.payload }}</td>
+          <td style="padding: 8px; color: #9fb2d0">{{ entry.correlation_id }}</td>
+        </tr>
+        {% endfor %}
+        {% else %}
+        <tr>
+          <td colspan="6" style="padding: 8px; color: #9fb2d0">No audit entries yet.</td>
+        </tr>
+        {% endif %}
+      </tbody>
+    </table>
+  </div>
+</div>

web/templates/partials/charts.html

@@ -0,0 +1,37 @@
+<div
+  id="charts-panel"
+  class="panel"
+  style="margin-top: 16px"
+  x-data="{ expanded: true }"
+>
+  <div class="chart-head">
+    <div>
+      <div class="label">Opportunity Trend</div>
+      <div class="meta">Recent opportunities from DuckDB. Updated {{ generated_at }}</div>
+    </div>
+    <button type="button" class="button secondary" x-on:click="expanded = !expanded">
+      <span x-text="expanded ? 'Hide chart' : 'Show chart'"></span>
+    </button>
+  </div>
+
+  <div x-show="expanded" x-transition style="margin-top: 16px">
+    <div class="card" style="padding: 12px">
+      {% if has_chart_data %}
+      <canvas id="opportunity-chart" class="chart-canvas"></canvas>
+      <script>
+        window.arbitradeRenderCharts(
+          {{ {
+            "has_chart_data": has_chart_data,
+            "labels": labels,
+            "net_pct_values": net_pct_values,
+            "est_profit_values": est_profit_values,
+            "cycles": cycles,
+          } | tojson }}
+        );
+      </script>
+      {% else %}
+      <div class="meta">No opportunity data yet.</div>
+      {% endif %}
+    </div>
+  </div>
+</div>

web/templates/partials/controls.html

@@ -0,0 +1,121 @@
+<div id="controls-panel" class="panel" style="margin-top: 16px">
+  <div class="grid">
+    <article class="card">
+      <div class="label">Runtime Status</div>
+      <div class="value">{{ execution_status }}</div>
+      <div class="meta">Updated {{ updated_at }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Kill Switch</div>
+      <div class="value">{{ kill_switch_status }}</div>
+      <div class="meta">Reason {{ kill_switch_reason }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Config Snapshot</div>
+      <div class="meta">Paper trading: {{ paper_trading_mode }}</div>
+      <div class="meta">Trade capital: {{ trade_capital_usd }}</div>
+      <div class="meta">Max trade capital: {{ max_trade_capital_usd }}</div>
+      <div class="meta">Max concurrent trades: {{ max_concurrent_trades }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Alerting</div>
+      <div class="meta">Status: {{ alerts_enabled }}</div>
+      <div class="meta">Channels: {{ alerts_channels }}</div>
+      <div class="meta">Min severity: {{ alerts_min_severity }}</div>
+      <div class="meta">Dedup window: {{ alerts_dedup_seconds }}s</div>
+      <div class="meta">Last result: {{ alerts_last_result }}</div>
+      <div class="meta">Last attempted: {{ alerts_last_attempted_at }}</div>
+      <div class="meta">Last success: {{ alerts_last_success_at }}</div>
+      <div class="meta">Last event: {{ alerts_last_event_title }}</div>
+      <div class="meta">Last error: {{ alerts_last_error }}</div>
+      {% if alerts_last_channel_results %} {% for item in
+      alerts_last_channel_results %}
+      <div class="meta">{{ item }}</div>
+      {% endfor %} {% endif %}
+    </article>
+  </div>
+
+  <div
+    class="grid"
+    style="
+      margin-top: 16px;
+      grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
+    "
+  >
+    <article class="card">
+      <div class="label">Execution Controls</div>
+      <div class="control-actions">
+        <form
+          hx-post="{{ start_endpoint }}"
+          hx-target="#controls-panel"
+          hx-swap="outerHTML"
+        >
+          <button type="submit" class="button">Start</button>
+        </form>
+        <form
+          hx-post="{{ stop_endpoint }}"
+          hx-target="#controls-panel"
+          hx-swap="outerHTML"
+        >
+          <button type="submit" class="button secondary">Stop</button>
+        </form>
+        <form
+          hx-post="{{ kill_switch_endpoint }}"
+          hx-target="#controls-panel"
+          hx-swap="outerHTML"
+        >
+          <input type="hidden" name="reason" value="manual" />
+          <button type="submit" class="button danger">
+            Trigger Kill Switch
+          </button>
+        </form>
+      </div>
+    </article>
+    <article class="card">
+      <div class="label">Edit Config</div>
+      <form
+        class="form-grid"
+        hx-post="{{ config_endpoint }}"
+        hx-target="#controls-panel"
+        hx-swap="outerHTML"
+      >
+        <label class="field">
+          <span>Trade capital USD</span>
+          <input
+            name="trade_capital_usd"
+            type="number"
+            min="0"
+            step="0.01"
+            value="{{ trade_capital_usd_value }}"
+          />
+        </label>
+        <label class="field">
+          <span>Max trade capital USD</span>
+          <input
+            name="max_trade_capital_usd"
+            type="number"
+            min="0"
+            step="0.01"
+            value="{{ max_trade_capital_usd_value }}"
+          />
+        </label>
+        <label class="field">
+          <span>Max concurrent trades</span>
+          <input
+            name="max_concurrent_trades"
+            type="number"
+            min="1"
+            step="1"
+            value="{{ max_concurrent_trades_value }}"
+          />
+        </label>
+        <label class="field checkbox">
+          {% set check = "checked" if paper_trading_mode == "enabled" else "" %}
+          <input name="paper_trading_mode" type="checkbox" {{ check }} />
+          <span>Paper trading mode</span>
+        </label>
+        <button type="submit" class="button">Save config</button>
+      </form>
+    </article>
+  </div>
+</div>

web/templates/partials/metrics.html

@@ -0,0 +1,31 @@
+<div id="metrics-panel" class="panel">
+  <div class="grid">
+    <article class="card">
+      <div class="label">Realized P&amp;L</div>
+      <div class="value">{{ realized_pnl }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Win Rate</div>
+      <div class="value">{{ win_rate }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Avg Trade Duration</div>
+      <div class="value">{{ avg_trade_duration }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Opportunities / Min</div>
+      <div class="value">{{ opportunities_per_minute }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Fill Rate</div>
+      <div class="value">{{ fill_rate }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Latency p50 / p95 / p99</div>
+      <div class="value">
+        {{ latency_p50 }} | {{ latency_p95 }} | {{ latency_p99 }}
+      </div>
+    </article>
+  </div>
+  <div class="meta">Updated {{ generated_at }}</div>
+</div>

web/templates/partials/overview.html

@@ -0,0 +1,67 @@
+<div id="overview-panel" class="panel" style="margin-top: 16px">
+  <div class="grid">
+    <article class="card">
+      <div class="label">Status</div>
+      <div class="value">{{ status }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Balances</div>
+      <div class="value">{{ balances }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Open Trades</div>
+      <div class="value">{{ open_trade_count }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Realized P&amp;L</div>
+      <div class="value">{{ realized_pnl_total }}</div>
+    </article>
+  </div>
+
+  <div
+    class="grid"
+    style="
+      margin-top: 16px;
+      grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
+    "
+  >
+    <article class="card">
+      <div class="label">Open Trades</div>
+      <ul>
+        {% for trade in open_trades %}
+        <li>
+          {{ trade.trade_ref }} - {{ trade.status }} - {{ trade.cycle }} - {{
+          trade.started_at }}
+        </li>
+        {% else %}
+        <li>No open trades.</li>
+        {% endfor %}
+      </ul>
+    </article>
+    <article class="card">
+      <div class="label">Balances Snapshot</div>
+      <div
+        class="value"
+        style="font-size: 1rem; font-weight: 500; word-break: break-word"
+      >
+        {{ balances }}
+      </div>
+      <div class="meta">Total value {{ total_value }}</div>
+    </article>
+    <article class="card">
+      <div class="label">Opportunity Feed</div>
+      <ul>
+        {% for opp in opportunities %}
+        <li>
+          {{ opp.cycle }} - {{ opp.net_pct }} - {{ opp.est_profit }} - {{
+          opp.detected_at }}
+        </li>
+        {% else %}
+        <li>No opportunities.</li>
+        {% endfor %}
+      </ul>
+    </article>
+  </div>
+
+  <div class="meta">Updated {{ generated_at }}</div>
+</div>